Origins, Phytochemistry, Pharmacology, Analytical Methods and Safety of Cortex Moutan (Paeonia suffruticosa Andrew): A Systematic Review

Abstract

Cortex Moutan (CM), a well-known traditional Chinese medicine, is commonly used for treating various diseases in China and other eastern Asian countries. Recorded in Pharmacopeias of several countries, CM is now drawing increasing attention and under extensive studies in various fields. Phytochemical studies indicate that CM contains many valuable secondary metabolites, such as monoterpene glycosides and phenols. Ample evidence from pharmacological researches suggest that CM has a wide spectrum of activities, such as anti-inflammatory, anti-oxidant, anti-tumor, anti-diabetic, cardiovascular protective, neuroprotective, hepatoprotective effects. Moreover, various analytical methods were established for the quality evaluation and safety control of CM. This review synopsizes updated information concerning the origins, phytochemistry, pharmacology, analytical method and safety of CM, aiming to provide favorable references for modern CM research and application. In conclusion, continuing pharmacological investigations concerning CM should be conducted to unravel its pharmacological mechanisms. Further researches are necessary to obtain comprehensive and applicable analytical approach for quality evaluation and establish harmonized criteria of CM.

Full text

molecules
Review
Origins, Phytochemistry, Pharmacology,
Analytical Methods and Safety of Cortex Moutan
(Paeonia suffruticosa Andrew): A Systematic Review
Zhiqiang Wang 1,2,3, Chunnian He 2,3, *, Yong Peng 2,3, Feihu Chen 1,* and Peigen Xiao 2,3
1School of Pharmacy, Anhui Medical University, Hefei 230032, China; wzqwillis1016@gmail.com
2Institute of Medicinal Plant Development, Chinese Academy of Medical Science,
Peking Union Medical College, Beijing 100193, China; ypeng@implad.ac.cn (Y.P.);
xiaopg@public.bta.net.cn (P.X.)
3Key Laboratory of Bioactive Substances and Resources Utilization of Chinese Herbal Medicine,
Ministry of Education, Beijing 100193, China
*Correspondence: cnhe@implad.ac.cn (C.H.); cfhchina@sohu.com (F.C.); Tel.: +86-10-5783-3165 (C.H.)
Academic Editor: Derek J. McPhee
Received: 17 May 2017; Accepted: 3 June 2017; Published: 7 June 2017
Abstract:
Cortex Moutan (CM), a well-known traditional Chinese medicine, is commonly used for
treating various diseases in China and other eastern Asian countries. Recorded in Pharmacopeias of
several countries, CM is now drawing increasing attention and under extensive studies in various
fields. Phytochemical studies indicate that CM contains many valuable secondary metabolites, such
as monoterpene glycosides and phenols. Ample evidence from pharmacological researches suggest
that CM has a wide spectrum of activities, such as anti-inflammatory, anti-oxidant, anti-tumor,
anti-diabetic, cardiovascular protective, neuroprotective, hepatoprotective effects. Moreover, various
analytical methods were established for the quality evaluation and safety control of CM. This review
synopsizes updated information concerning the origins, phytochemistry, pharmacology, analytical
method and safety of CM, aiming to provide favorable references for modern CM research and
application. In conclusion, continuing pharmacological investigations concerning CM should be
conducted to unravel its pharmacological mechanisms. Further researches are necessary to obtain
comprehensive and applicable analytical approach for quality evaluation and establish harmonized
criteria of CM.
Keywords:
Cortex Moutan; origins; phytochemistry; pharmacology; safety; Traditional Chinese Medicine
1. Introduction
Traditional Chinese Medicine (TCM) plays an indispensable role in the healthcare system of
Chinese people due to its efficiency for various diseases, and still contributes to satisfy the modern
medical demand owing to its large-scale compounds reservoir for new drug discovery. Cortex
Moutan (CM), dried root bark of Paeonia suffruticosa Andrew (Fam. Ranunculaceae/Paeoniaceae), is an
important crude drug traditionally used in China to treat diverse diseases for thousands of years [
1
].
P. Suffruticosa, called “Mudan” in Chinese vernacular names, is equally famous for its ornamental
and medicinal uses: its flower is a symbol of elegance and prosperity, while its root bark, namely
“Mudanpi” in Chinese, is broadly used in TCM as remedies for cardiovascular, extravasated blood,
stagnated blood, and female genital diseases [
2
]. CM was recorded in several famous Chinese medical
books, like Compendium of Materia Medica (Ben Cao Gang Mu), Shen Nong
'
s Herbal Classic (Shen Nong
Ben Cao Jing) and Chinese Materia Medica (Zhong Hua Ben Cao), etc. In addition, it is widely used in
eastern Asian countries and recorded in Pharmacopeias of several countries, such as China, Japan,
Molecules 2017,22, 946; doi:10.3390/molecules22060946 www.mdpi.com/journal/molecules

Molecules 2017,22, 946 2 of 27
Korea and Vietnam. In the theory of TCM, it is believed that CM alleviates sickness in humans by
clearing excessive heat, cooling the blood, promoting blood circulation, and removing blood stasis
without inducing bleeding. CM was applied in a great number of prescriptions, exemplified as “Liuwei
Dihuang wan” for yin deficiency; “Guizhi Fuling wan” and “Wen Jin tang” for chronic female diseases;
“Ba Wei tang” for disease of the aged, like diabetes and arteriosclerosis; and “Dahuang Mudan tang” for
appendicitis and carbuncles [
3
]. There are 79 CM containing preparations in Chinese Pharmacopoeia
(2015 edition). Moreover, CM was found in 13 formulations recorded in Taiwan Herbal Pharmacopoeia
(Second edition, Chinese version) and 8 commonly used kampo medicines [4].
Given its wide application, CM is now being extensively studied in phytochemistry, pharmacology
and chemical analysis. Last several decades have saw plethora of papers reporting isolation and
identification of many components in CM extracts, notablely paeonol, paeoniflorin, paeonoside,
apiopaeonoside, oxypaeoniflorin, galloylpaeoniflorin, galloyloxypaeoniflorin, mudanpioside A, B,
C, D, E, H, suffruticoside A, B, C, D, E, benzoyloxypaeoniflorin, benzoylpaeoniflorin and gallic acid,
etc. [
5
,
6
]. Meanwhile, it is reported that CM extracts have a wide spectrum of pharmacological
activities, including anti-inflammatory [
7
,
8
], anti-allergic [
9
,
10
], and anti-oxidative effects [
11
,
12
]. For
the chemical analysis of CM, many qualitative and quantitative methods, such as high performance
liquid chromatography (HPLC), gas chromatography (GC), capillary electrophoresis (CE), and liquid
chromatography tandem mass spectrometry (LC-MS), are established for the comprehensive quality
evaluation of CM. HPLC methods are often established for multi-components assaying simultaneously,
and LC-MS methods greatly support unambiguous identification and high sensitive quantifications of
compounds at trace concentrations.
Nevertheless, as herbal medicine with complicated compounds, quality evaluation and quality
control of CM remain challenging for modern researchers and TCM practitioners. In China, CM
was produced from different origins with different processing methods. Therefore, discrepancies in
chemical composition of different CM may exist. Moreover, in the general market, CM is only graded
by various aspects of their physical appearances, such as root length and diameter. Besides, confusion
remains about the pharmacological mechanism of CM, as therapeutic effects of TCMs often come
as a result of synergistic effects of multi-compounds. However, quality criteria for CM in Chinese
Pharmacopeia and other East Country Pharmacopoeias rely on only a single or a few constituents as
chemical makers, such as paeonol and paeoniflorin. In fact, only detecting paeonol and paeoniflorin is
at best partial and inadequate to reflect the holistic quality of CM.
This review intent to compile various researches and critically summarize the issues related
to origins, phytochemistry, pharmacology, analytical methods and safety about CM. The isolated
bioactive constituents and reported biological activities of CM over the past few decades are synopsized.
Analytical methods concerning CM in recent years are also outlined. Overall, the aim of this review is
to provide favorable references for the modern application and research of CM, such as quality control,
quality evaluation and standard improvement during production and processing, etc.
2. Origins of CM
According to Chinese Pharmacopoeia, the original plant of CM is always considered to be
P. suffruticosa Andrews, which is the collective name of cultivated tree peonies [
13
]. Recently, as the
botanists further refine the taxonomy, section Moutan DC of the genus Paeonia L. in the family
Paeoniaceae were generally subdivided into nine wild shrubby species: P. cathayana,P. decomposita,
P. jishanensis,P. ostii,P. qiui,P. rockii,P. rotundiloba,P. delavayi and P. ludlowii [
14
]. Based on the botanist’s
view, cultivated tree peonies, originated from the hybridization of multiple species of wild tree peonies,
belong to P. suffruticosa complex. Besides, the cultivated P. ostii is also widely grown and considered
major source of CM. Therefore, successive version of Chinese Pharmacopoeia regulate that the original
plant for CM is P. suffruticosa(s.l.), which includes P. ostii and P. suffruticosa [
15
]. P. suffruticosa(s.l.)
is mainly cultivated in different areas with different vernacular names: CM in Tongling (Anhui
province) is called “Feng Danpi”, CM in Dianjiang (Sichuan province) is called “Chuan Danpi” and

Molecules 2017,22, 946 3 of 27
CM in Heze (Shandong province) is called “Cao Danpi”. In addition, root cortex of several wild tree
peonies, such as P. decomposita,P. delavayi,P. rockii,P. jishanensis, are used as substitute of CM due to
morphological similarity in different regions of China. For example, root cortex of P. delavayi Franch,
called “Diandanpi”, is often used in Yunnan province as a folk medicines substituting CM. In general,
the root of P. suffruticosa(s.l.) is often collected in autumn, removed from rootlets and soil, and then
manufactured into two forms of official drug of CM, Liandanpi and Guadanpi, with different process
method respectively. In the former method the root bark is stripped off, and dried in the sun, while in
the latter method scrape off tertia, removed from duramen then dehydrated in the sun [
13
] (Figure 1).
Molecules 2017, 22, 946 3 of 26
of several wild tree peonies, such as P. decomposita, P. delavayi, P. rockii, P. jishanensis, are used as
substitute of CM due to morphological similarity in different regions of China. For example, root
cortex of P. delavayi Franch, called “Diandanpi”, is often used in Yunnan province as a folk
medicines substituting CM. In general, the root of P. suffruticosa(s.l.) is often collected in autumn,
removed from rootlets and soil, and then manufactured into two forms of official drug of CM,
Liandanpi and Guadanpi, with different process method respectively. In the former method the root
bark is stripped off, and dried in the sun, while in the latter method scrape off tertia, removed from
duramen then dehydrated in the sun [13] (Figure 1).
Figure 1. (a) Plants of P. suffruticosa; (b) Crude drug of Guadanpi; (c) Decoction pieces of Cortex Moutan
(CM).
3. Chemistry of CM
To our current best knowledge, 119 compounds have been isolated and structurally identified from
CM, which can be assigned to seven classes: monoterpenes, monoterpene glycosides, flavonoids,
tannins, triterpenoids, phenols and others [16–28]. Monoterpene glycosides and phenols are
predominant constituents in CM (Figure 2 and Table S1).
3.1. Monoterpenes and Monoterpene Glycosides
A total of 10 monoterpenes, 1–8, 10, 11, and 52 monoterpene glycosides, 9, 12–62, were reported
from CM. The absolute stereostructures of paeonisuffrone (4), paeonisuffral (3), paeonisothujone (7),
deoxypaeonisuffrone (5) and isopaeonisuffral (3) have hitherto been reported [29,30]. Paeonisothujone
(7) is the first natural example of ortho-menthane-type monoterpene having a cyclopropane ring and
paeonisuffrone (4) is a tricyclic compound [31].
Monoterpene glycosides, such as paeoniflorin (12) and its analogues 13–62, were ubiquitous
chemical components across all species of the genus Paeonia which possesses a “cage-like” pinnae
skeleton. Compounds 13–62 are pinnae type derivatives resembled closely to each other, the
common pattern is a pinnae skeleton with a aglycone and one or two different moieties with a
variety of substituent groups, like benzoyl, galloyl, p-hydroxybenzoyl, vanilloyl, etc. For example,
mudanpioside A–E (18–22) were mono- or di-benzoates of monoterpene glycosides. The difference
between them lies in the substitution pattern of the aromatic rings [32]. Recently, new monoterpene
glycosides are continuingly reported, such as paeoniside A (41) and paeoniside B (42). Paeoniside A
(41) has a monoterpene system and same aglycone of paeoniflorin (12) togother with two benzoyl
moieties, while the structure of paeoniside B (42) was very similar to paeoniside A (41), except for
the absence of a benzoyl moiety and the appearance of galloyl moiety [33]. It was reported in 2012
that suffruyabiosides A and B (39,40) were rare two new monoterpene diglycosides with a cellobiose
in the molecules[34]. Among all the identified monoterpene glycosides, several pairs of isomers
were found. For instance, α-benzoyloxypaeoniflorin (28) and β-benzoyloxypaeoniflorin (29),
benzoylpaeoniflorin (17) and paeoniside A (41) are α- and β-anomers, respectively. Suffrupaeonidanin D
(34) and paeonidanin A (37), oxypaeonidanin (45) and 9-epi-oxypaeonidanin (46) are unambiguously
confirmed chiral isomers, respectively.
Figure 1.
(
a
) Plants of P. suffruticosa; (
b
) Crude drug of Guadanpi; (
c
) Decoction pieces of Cortex
Moutan (CM).
3. Chemistry of CM
To our current best knowledge, 119 compounds have been isolated and structurally identified
from CM, which can be assigned to seven classes: monoterpenes, monoterpene glycosides, flavonoids,
tannins, triterpenoids, phenols and others [
16
–
28
]. Monoterpene glycosides and phenols are
predominant constituents in CM (Figure 2and Table S1).
3.1. Monoterpenes and Monoterpene Glycosides
A total of 10 monoterpenes,
1
–
8
,
10
,
11
, and 52 monoterpene glycosides,
9
,
12
–
62
, were reported
from CM. The absolute stereostructures of paeonisuffrone (
4
), paeonisuffral (
3
), paeonisothujone (
7
),
deoxypaeonisuffrone (
5
) and isopaeonisuffral (
3
) have hitherto been reported [
29
,
30
]. Paeonisothujone
(
7
) is the first natural example of ortho-menthane-type monoterpene having a cyclopropane ring and
paeonisuffrone (4) is a tricyclic compound [31].
Monoterpene glycosides, such as paeoniflorin (
12
) and its analogues
13
–
62
, were ubiquitous
chemical components across all species of the genus Paeonia which possesses a “cage-like” pinnae
skeleton. Compounds
13
–
62
are pinnae type derivatives resembled closely to each other, the common
pattern is a pinnae skeleton with a aglycone and one or two different moieties with a variety of
substituent groups, like benzoyl, galloyl, p-hydroxybenzoyl, vanilloyl, etc. For example, mudanpioside
A–E (
18
–
22
) were mono- or di-benzoates of monoterpene glycosides. The difference between them
lies in the substitution pattern of the aromatic rings [
32
]. Recently, new monoterpene glycosides
are continuingly reported, such as paeoniside A (
41
) and paeoniside B (
42
). Paeoniside A (
41
) has a
monoterpene system and same aglycone of paeoniflorin (
12
) togother with two benzoyl moieties, while
the structure of paeoniside B (
42
) was very similar to paeoniside A (
41
), except for the absence of a
benzoyl moiety and the appearance of galloyl moiety [
33
]. It was reported in 2012 that suffruyabiosides
A and B (
39
,
40
) were rare two new monoterpene diglycosides with a cellobiose in the molecules [
34
].
Among all the identified monoterpene glycosides, several pairs of isomers were found. For instance,
α
-benzoyloxypaeoniflorin (
28
) and
β
-benzoyloxypaeoniflorin (
29
), benzoylpaeoniflorin (
17
) and
paeoniside A (
41
) are
α
- and
β
-anomers, respectively. Suffrupaeonidanin D (
34
) and paeonidanin
A (
37
), oxypaeonidanin (
45
) and 9-epi-oxypaeonidanin (
46
) are unambiguously confirmed chiral
isomers, respectively.

Molecules 2017,22, 946 4 of 27
Molecules 2017, 22, 946 4 of 26
Figure 2. Cont.
Figure 2. Cont.

Molecules 2017,22, 946 5 of 27
Molecules 2017, 22, 946 5 of 26
Figure 2. Cont.
Figure 2. Cont.

Molecules 2017,22, 946 6 of 27
Molecules 2017, 22, 946 6 of 26
Figure 2. Cont.
Figure 2. Cont.

Molecules 2017,22, 946 7 of 27
Molecules 2017, 22, 946 7 of 26
Figure 2. Cont.
Figure 2. Cont.

Molecules 2017,22, 946 8 of 27
Molecules 2017, 22, 946 8 of 26
Figure 2. Chemical structures of 119 compounds isolated from CM.
3.2. Flavonoids and Tannins
To date, seven flavonoids 63–69 and three tannins 70–72 were obtained from CM. Flavonoids
reported from CM are quercetin (63), kaempferol (65), catechin (64) and catechin derivatives (66–69).
Tannins found in CM are galloyl glucoses, they are 1,2,3,4,6-Penta-O-galloyl-β-D-glucose(PGG, 70),
trigalloyl-glucoses (71) and (−)-Epigallocatechin gallate (72) [35–37].
3.3. Phenols
A total of 29 phenols were isolated from CM. Phenols 83–111, especially acetophenones (99, 105,
107–110), are the characteristic metabolites mainly reported from P. suffruticosa and present in
P. albiflora and P. lactiflora in scarcely low levels. Paeonol (83) and paeonol glycosides, like paeonoside
(84), paeonolide (85), apiopaeonoside (91) and suffruticoside A–E (86–90), are characteristic and major
components in CM. Some of the phenols, such as gallic acid (97), benzoic acid (104) are distributed
widely in Paeonia. Recently, several new phenols were reported from P. suffruticosa, they are
mudanoside C (102), iriflophenone 2-O-β-D-glucopyranoside (111) [38].
3.4. Triterpenoids and Others
So far, 10 triterpenoids, 73–82, and other compounds, 112–119 have been reported from CM. 73–76
are tetracyclic triterpenoids whereas 77–82 are pentacyclic triterpenoids. Other compounds, like
adenosine (112), uridine (113), 1-tryptophan (114), thymidine (115), ainsliaside E (116), and
paesuffrioside (117) were reported to be present in CM water-soluble constituents [39].
Figure 2. Chemical structures of 119 compounds isolated from CM.
3.2. Flavonoids and Tannins
To date, seven flavonoids
63
–
69
and three tannins
70
–
72
were obtained from CM. Flavonoids
reported from CM are quercetin (
63
), kaempferol (
65
), catechin (
64
) and catechin derivatives (
66
–
69
).
Tannins found in CM are galloyl glucoses, they are 1,2,3,4,6-Penta-O-galloyl-
β
-D-glucose (PGG,
70
),
trigalloyl-glucoses (71) and (−)-Epigallocatechin gallate (72) [35–37].
3.3. Phenols
A total of 29 phenols were isolated from CM. Phenols
83
–
111
, especially acetophenones (
99
,
105
,
107
–
110
), are the characteristic metabolites mainly reported from P. suffruticosa and present in
P. albiflora and P. lactiflora in scarcely low levels. Paeonol (
83
) and paeonol glycosides, like paeonoside
(
84
), paeonolide (
85
), apiopaeonoside (
91
) and suffruticoside A–E (
86
–
90
), are characteristic and
major components in CM. Some of the phenols, such as gallic acid (
97
), benzoic acid (
104
) are
distributed widely in Paeonia. Recently, several new phenols were reported from P. suffruticosa, they
are mudanoside C (102), iriflophenone 2-O-β-D-glucopyranoside (111) [38].
3.4. Triterpenoids and Others
So far, 10 triterpenoids,
73
–
82
, and other compounds,
112
–
119
have been reported from CM.
73
–
76
are tetracyclic triterpenoids whereas
77
–
82
are pentacyclic triterpenoids. Other compounds,
like adenosine (
112
), uridine (
113
), 1-tryptophan (
114
), thymidine (
115
), ainsliaside E (
116
), and
paesuffrioside (117) were reported to be present in CM water-soluble constituents [39].

Molecules 2017,22, 946 9 of 27
4. Pharmacological Activities of CM
4.1. Anti-Oxidative Effects
Reactive oxygen species (ROS) plays a central role in causing various types of diseases.
The mechanism of CM to inhibit ROS production was studied intensively. The EtOH extract of
CM inhibited the production of ROS on oxidative-stressed PC12 cells [
11
]. Besides, it was reported that
total phenolic contents in methanol extracts of CM possessed significant antioxidant capacities and
thus could be potential rich sources of natural antioxidants [
40
]. A significant relationship between
antioxidant capacities and total phenolic contents were found, indicating that phenolic components are
major contributor of antioxidant activities in CM. Paeonol (
83
), the predominant phenolic compound in
CM, was reported to possess a variety of therapeutic properties by virtue of its free radical scavenging
properties, for instance, paeonol (
83
) improved antioxidant defense system through the activation
of Nrf2 related pathway in isoproterenol-induced myocardial infarction model [
41
] and attenuated
cigarette smoke-induced lung inflammation via its antioxidant function and an inhibition of the
MAPKs/NF-κB signaling [42].
Furthermore, paeoniflorin (
12
), a well-known extracellular ROS scavenger, exerts cytoprotective
effects against
60
Co-ray-induced oxidative damage in thymocytes [
43
] and protects EA.hy926 cells
against radiation-induced injury through the Nrf2/HO-1 pathway [
44
], indicating that paeoniflorin
(
12
) offers a potential application in treating radiation-induced injury. Literatures also suggest that
paeoniflorin (
12
) protects retinal pigment epithelium cells from oxidative stress [
45
]. Moreover,
Galloylpaeoniflorin (
15
), galloylated derivate of paeoniflorin, showed cytoprotective effects against
hydrogen peroxide (H
2
O
2
)-induced cell injury and death in human HaCaT keratinocytes [
46
]. Above
all, ingredients of CM can significantly alleviate oxidative stresses and decrease ROS production.
However, the above studies are largely carried on different cell lines, animal model or clinical tests are
required in future investigations.
4.2. Anti-Inflammatory Effects
Published reports consistently demonstrate that CM possesses anti-inflammatory effects. Several
in vivo
and
in vitro
model stimulated by lipopolysaccharides (LPS) have been developed to study the
anti-inflammation effect of CM and its principal components. For example, administration of CM prior
to LPS challenge improves acute lung injury mediating through anti-inflammation in rat models [
2
].
And CM has anti-inflamamatory effects through the inhibition of iNOS and COX-2 expression by
suppressing the phosphorylation of I-
κ
B
α
and the activation of NF-
κ
B in LPS-Activated macrophage
cells [
47
]. The expression levels of LPS-induced genes in macrophages were altered, to different extents,
by treatment with paeonol (
83
), paeoniflorin (
12
), and albiflorin (
14
) [
48
]. Moreover, inflammatory
changes of gene expression in LPS-stimulated gingival fibroblasts was studied using a genome-wide
expression GeneChip, results suggest CM inhibits the induction of inflammation by comprehensively
inhibiting a wide variety of activations of inflammation-related genes, which may be due to paeonol
(
83
) and paeonoflorin (
12
) [
8
]. Besides, paeoniflorin (
12
) was proven to exert anti-inflammatory
effect in animal models of collagen-induced arthritis, ischemia/reperfusion-induced cerebral injury,
LPS-induced acute lung injury and liver inflammatory reactions. For example, paeoniflorin (
12
) inhibits
LPS-induced inflammation in human umbilical vein endothelial cells concomitantly with decreased
expression of the enhanced high mobility group box-1 (HMGB1), downregulated mRNA and protein
expression of RAGE, TLR-2 and TLR-4, and decreased NF-κB activity [49].
CM can significantly inhibit the secretion of inflammatory chemokines in several cell lines and
a rat model. Methanolic extract of CM, specifically PGG (
70
), markedly suppressed secretions
of IL-8 and macrophage chemo-attractant protein-1 in human monocytic U937 cells stimulated
with phorbol myristate acetate [
50
]. Paeoniflorin (
12
), paeonol (
83
), and PGG (
70
) exhibited
dose-dependent inhibition of TNF-
α
synthesis and IL-6 production in synoviocytes treated with
pro-inflammatory mediator [
7
]. Besides, it was reported that paeonol (
83
) suppressed LPS-induced

Molecules 2017,22, 946 10 of 27
inflammatory cytokines in macrophage cells and protected mice from lethal endotoxin shock.
In vitro
study suggests paeonol (
83
) down regulated the production of TNF-
α
, IL-1
β
, IL-6, and IL-10 via
inactivation of I-
κ
B
α
, ERK1/2, JNK, and p38 MAPK. Moreover, paeonol (
83
) significantly regulates
pro- and anti-inflammatory cytokines in mouse model of LPS-induced endotoxemia [
51
]. However,
bioavailability of these identified compounds are not good enough; it can be anticipated that new
synthetic agents derived from active compounds in CM can have good bioavailability.
4.3. Anti-Tummor Effects
Various researches have been conducted on anti-tumor effects of CM in recent years.
Antiproliferative effects of CM on human cancer cell lines encompasses several common malignancies,
such as breast ductal carcinoma, colon cancer, hepatocellular carcinoma, gastric cancer, and esophageal
cancer [
52
,
53
]. CM extract blocks the binding of vascular endothelial growth factor (VEGF),
an important angiogenic molecule, to VEGF receptor and reduce VEGF-induced endothelial cell
proliferation [
54
]. As we know, angiogenesis plays a critical role in tumor growth and metastasis
processes. It is suggested that CM may be used as a candidate for developing anti-angiogenic agent.
Researches also revealed that CM exhibited high selectivity in inhibiting the growth of bladder cancer
cells and reduced the expression of angiogenesis-stimulating factors, including VEGF [55].
Recently, several compounds involved in anti-tumor effects of CM were investigated. Paeonol
(
83
) was reported to suppress chondrosarcoma metastasis [
56
] and melanoma metastasis [
57
]. Several
studies indicate that paeonol (
83
) induces tumor cell apoptosis in HepG2 cells [
58
], mice bearing
EMT6 breast carcinoma [
59
] and a HepA-hepatoma bearing mouse model [
60
]. Moreover, paeonol (
83
)
reverses paclitaxel resistance in human breast cancer cells by regulating the expression of transgelin
2 [
61
] and exerts an anticancer effect on human colorectal cancer cells through inhibition of PGE2
synthesis and COX-2 expression [
62
]. Paeoniflorin (
12
) inhibits proliferation and invasion of breast
cancer cells [
63
] and macrophage-mediated lung cancer metastasis [
64
]. In addition, paeoniflorin (
12
)
inhibits proliferation and induces apoptosis of human glioma cells via microRNA-16 upregulation and
matrix metalloproteinase-9 downregulation [
65
]. PGG (
70
) exhibits
in vitro
anti-proliferative effect on
human hepatocellular carcinoma cell line, SK-HEP-1 cells [
66
]. In conclusion, paeonol (
83
), paeoniflorin
(
12
) and PGG (
70
) cause no significant cytotoxic effects to normal cell lines, these compounds can
be vital sources of adjuvant agent or complementary medicine during systemic chemotherapy in
treating cancers.
4.4. Cardiovascular System Protective Effects
CM has been frequently used as an important ingredient in traditional prescriptions to relieve
cardiovascular diseases, like Shuangdan granule, which has been authorized by SFDA of China to
treat acute heart ischemia [
67
]. In TCM, CM has been commonly used to promote blood circulation
and alleviate blood stasis. Nowadays, there is a growing awareness of the therapeutic potential of
CM in cardiovascular system, and cardio-protective effects of CM are under extensive investigations.
In a recent study, CM has been shown to protect the myocardium from ischemia/reperfusion injury
by restoring the anti-oxidative defense system and increasing the expression of anti-apoptotic gene
Bcl-2 [
68
]. Besides, paeonol (
83
) protects rat heart by improving regional blood perfusion during
no-reflow [69].
The mechanism underlying the vasodilatatory effects of paeonol was investigated, an intracellular
Ca
2+
regulatory mechanism may be responsible for potent vasodilatory effect of paeonol [
70
]. Both
paeonol (
83
) and paeoniflorin (
12
) have the potential to improve prethrombotic state and recanalize
thrombi [
71
,
72
]. Furthermore, paeonol (
83
) has potential protective effects on the development of
atherosclerosis through inhibiting oxidized low density lipoprotein-induced monocyte adhesion to
vascular endothelial cell by inhibiting the mitogen activated protein kinase pathway [
73
]. Paeoniflorin
(
12
) ameliorates acute myocardial infarction of rats by inhibiting inflammation and inducible
nitric oxide synthase signaling pathways [
74
] and suppresses vascular damage and the expression

Molecules 2017,22, 946 11 of 27
of E-selectin and ICAM-1 in a mouse model of cutaneous Arthus reaction [
75
]. In summary,
paeonol (
83
), paeoniflorin (
12
), benzoylpaeoniflorin (
17
), and
α
-benzoyloxypaeoniflorin (
28
) were
found to be the major common active constituents and they would collectively contribute to
improving blood circulation through their inhibitory effects on both platelet aggregation and blood
coagulation. In addition, me gallate (
98
), catechin (
64
), paeoniflorigenone (
1
), galloylpaeoniflorin
(
15
), and daucosterol (
74
) might also play a role in cardiovascular protective effects of CM [
76
].
More comprehensive animal and clinical studies should be conducted for the purpose of elucidating
the therapeutic mechanism of CM on cardiovascular diseases.
4.5. Anti-Diabetic Activity
CM is a well-known herb found in anti-diabetic traditional medicine formulae, such as Liuwei
Dihuang pills (LDP) [
77
]. Recently, scientific investigations about the extract of CM and its component
are accumulating to explore its possible anti-diabetic mechanisms. Extraction of CM ameliorates the
oxidative stress and inflammation in AGEs-induced mesangial cell dysfunction and streptozotocin
(STZ)-induced diabetic nephropathy rats (DN) [
12
,
78
]. It is also reported that CM and its active
component, especially paeonol (
83
), showed significant
in vitro
anti-diabetic effects by inhibiting
glucose uptake of intestinal brush border membrane vesicles and enhancing glucose uptake into Hs68
and 3T3-L1 cells [
79
]. Furthermore, studies suggests paeonol (
83
) could improve the pathological
damage of diabetic encephalopathy (DE) in STZ-induced diabetic rats through AGEs/RAGE/NF-
κ
B
pathway [
80
]. Paeoniflorin (
12
) has an anti-inflammatory effect in diabetic kidneys and prevents the
development of nephropathy [
81
]. In addition, palbinone (
76
) and triterpenoids (
73
,
74
,
78
,
79
,
81
,
82
)
remarkably stimulated glucose uptake and glycogen synthesis via AMPK pathway in a dose-depended
manner. These compounds may have considerable potential for relieving the metabolic abnormalities
associated with diabetic diseases [
82
]. In a word, most, if not all the active components of CM
responsible for the hypoglycemic effect have been investigated and reported. CM can markedly
improve glucose metabolism [
83
], attenuate diabetic syndromes like DE, DN and diabetic cataract [
84
].
4.6. Neuroprotective Activity
CM is now drawing increasing attention because of its neuroprotective activity. Many
pharmacological investigations of CM have been addressed to elucidate the neuroprotective effects and
underlying mechanisms of CM. According to previous studies, CM exhibits effectiveness in alleviating
neuropathic pain [
85
] and neurodegenerative diseases, such as Parkinson disease [
86
]. Among
compounds reported in CM, paeonol (
83
) and paeoniflorin (
12
) are well-known agents that have shown
neuro-associated activities. Paeonol protected neurons from oxygen-glucose deprivation-induced
injuries [
87
] and neurotoxicity caused by H
2
O
2
treatment [
88
]. Moreover, another study implied that
inhibition of NF-
κ
B translocation to the nucleus and suppression of the mitogen activated protein
kinase activities were involved in the anti-neuroinflammatory effects of paeonol (
83
) [
89
]. Paeonol
(
83
) inhibits inflammatory and oxidative mediators in microglial cell through activation of AMPK
α
and GSK3
α
/
β
signaling pathway [
90
]. Also, paeonol (
83
) significantly improved cognitive deficit
and neuropathologic lesion induced by D-gal injection in mice [
91
]. Following 6-hydroxydopamine
toxicity in neuronal cells, paeonol (
83
) increases cell viability by inhibiting ROS production and
increasing superoxide dismutase activity and Bcl-2 expression [
92
]. Treatment with paeonol (
83
) can
protect against many of the alterations, including morphological, biochemical and behavioral changes,
resulting from administration of Aβ1–42 in a rat model of Alzheimer’s disease [93].
Recent investigations have demonstrated that paeoniflorin (
12
) administration can attenuate
ischemia-induced cerebral injuries in rodent models [
94
] and alleviate glutamate or LPS-induced
neuronal lesions [
95
]. Following glutamate, MPTP, and 6-hydroxydopamine toxicities, paeoniflorin
(
12
) attenuates dopaminergic neuronal damage and behavioral impairments via the regulation of
Bcl-2 family proteins and the inhibition of neuro-inflammation,
in vitro
and
in vivo
[
96
–
98
]. Moreover,
paeoniflorin (
12
) protects neuronal cells from neurotoxins via an autophagic pathway and results

Molecules 2017,22, 946 12 of 27
in the degradation of
α
-synuclein [
99
]. Paeoniflorin (
12
) also inhibits 6-hydroxydopamine-induced
apoptosis in PC12 cells via suppressing ROS-mediated PKC
δ
/NF-
κ
B pathway [
100
]. Neuroprotective
effects of paeoniflorin (
12
), but not the isomer albiflorin (
14
), are associated with the suppression of
intracellular calcium and calcium/calmodulin protein kinase II in PC12 cells [
101
]. Besides, PGG (
70
)
have strong inhibitory effects on formation of A
β
fibrils
in vitro
and
in vivo
[
102
] and protects rat
neuronal cells (Neuro 2A) from hydrogen peroxide-mediated cell death via the induction of heme
oxygenase-1 [
103
]. The current findings suggest that CM may be useful as alternative therapy to
prevent and treat dopaminergic neuron dysfunctions [86].
4.7. Hepatoprotective Activity
Accumulating evidence indicates that CM has hepatoprotective activities. Pre-exposure of CM
may attenuate acetaminophen-induced cytotoxicity through alleviation of GSH depletion, cytochrome
P4502E1 activity, and hepatic DNA damage
in vivo
[
104
]. Paeonol (
83
) alleviates epirubicin-induced
hepatotoxicity in 4T1-tumor bearing mice by inhibiting the PI3K/Akt/NF-
κ
B pathway [
105
] and
ameliorates alcoholic steatohepatitis in mice [
106
]. Pretreatment of paeoniflorin (
12
) protects mice
against concanavalin A-induced hepatitis via inhibition of several inflammatory mediators and
downregulation of the NF-
κ
B pathways [
107
]. Besides, paeoniflorin (
12
) alleviates liver fibrosis
by inhibiting HIF-1
α
through mTOR-dependent pathway [
108
]. Above all, CM is traditionally used
as dietary supplement or TCM to treat hepatitis, and the above investigations may provide scientific
explanations for the traditional application.
4.8. Others
Increasing studies suggest that CM possesses a broad range of other biological activities like
anti-bacterial [
109
,
110
], anti-allergic [
9
,
111
], immunomodulatory [
112
], anti-fungal [
113
] and alleviating
colitis [
114
]. Moreover, Paeoniflorin (
12
) promotes non-rapid eye movement sleep via adenosine [
115
].
Several studies were carried out to screen bioactive compounds in CM.
In vitro
experiment
verified that paeoniflroin (
12
), PGG (
70
), and paeonol (
83
) reduced the activity of nicotinamide-adenine
dinucleotide phosphate oxidase (NADPH) activity and decreased the level of ROS [
116
]. Similarly,
in order to analyze the bioactive compounds in CM on treating nephropathy, mouse renal mesangial
cells were cultured and used to bind and separate components in CM extraction. One compound
which could interact with mesangial cells was found and identified as paeonol (
83
) [
117
]. In summary,
CM has exhibited various pharmacological benefits; it can be a promising alternative or adjuvant
therapy for various diseases.
5. Analytical Methods for Quality Evaluation of CM
5.1. Quality Criteria of CM in Different Countries
There are slight differences in the nomenclature and some aspects of the use of CM in different
Pharmacopoeias, such as Chinese Pharmacopoeia, Japanese Pharmacopoeia, Korean Pharmacopoeia,
Vietnamese Pharmacopoeia, Hong Kong Chinese Materia Medica Standards and Taiwan Herbal
Pharmacopoeia [
118
]. Descriptions of CM, like length, diameter and thickness, vary from each other
too. However, the testing methods and specification values for CM vary significantly in different
pharmacopoeias. For instance, criteria for CM in Chinese Pharmacopoeia stipulate that the content
of paeonol (
83
) and ethanol-soluble extractives must be higher than 1.2%, 15.0% respectively, and
the moisture and total ash should be no more than 13.0% and 5.0% separately. In comparison, HP
ruled that the content of paeonol (
83
) and paeoniflorin (
12
) should not be less than 0.49% and 1.1%
respectively, while the JP Sixteenth Edition demands that CM contains not less than 1.0% of paeonol
(
83
). In addition, TLC and HPLC assay conditions vary significantly in six pharmacopoeias, too
(Table S2). To conclude, current quality criteria of CM are based on a single or a few chemical markers,
which fails to reflect the overall quality of CM.

Molecules 2017,22, 946 13 of 27
5.2. Qualitative and Quantitative Analysis of CM
5.2.1. Thin-Layer Chromatography (TLC) Analysis
TLC analysis is simple, economical and reliable. For reasons of safety, efficacy and quality control,
El Babili et al. developed a TLC and microscopic identification technique that systematically studied
three species, namely P. suffruticosa (tree peony), Paeonia lactiflora and Paeonia veitchii [
119
]. This
method provides a simple, inexpensive and unambiguous way for establishing the authentication of
three similar peony species. Furthermore, when combined with digital scanning and documentation
software, TLC provides much more information and parameters. After extraction of CM with ether
and ethanol respectively, obtained solutions were separated and analyzed in a TLC solvent system to
establish TLC fingerprint, then the TLC plate was scanned under dual wavelength TLC scanner to
obtain the quantitative data of characteristic peaks, which subsequently drawn to a column diagram
that can intuitively reflect the internal quality of CM [
120
]. However, the biggest problem of TLC lies
in the poor accuracy and low reproducibility.
5.2.2. HPLC Analysis
HPLC analysis for CM usually focuses on phenols, monoterpene glycosides and flavonoids, such
as paeonol (
83
), paeonolide (
85
), apiopaeonoside (
91
), gallic acid (
97
), PGG (
70
), paeoniflorin (
12
),
oxypaeoniflorin (
13
), catechin (
64
), etc., since these compounds have been proven to exhibit many
biological activities and contributes to overall therapeutic effects of CM. The separation was often
carried out on reverse-phase C18 columns with binary gradient elution.
Among all the detectors hyphenated to HPLC, UV or DAD are the most commonly applied
detectors. Different types of compounds in CM exhibit specific UV absorption characteristics
respectively. Monoterpene compounds, often esterified with an aromatic acid such as benzoic acid
(
104
), p-hydroxybenzoic (
93
) acid and gallic acid (
97
), expose consistent maximum UV absorption
wavelengths with these aromatic acid because neither the pinnae skeleton nor glucose moiety shows UV
absorption. Two absorption peaks of flavonoids at 330–360 and 250–270 nm originate from their B and
A rings, respectively. Paeonol (
83
) and its derivatives generally display three absorption maxima bands
at 225–230, 270–280 and 300–320 nm, respectively [121]. In order to determine various compounds at
its peak absorbance wavelength, UV switch methods simultaneously monitoring multiple wavelength
were used [
122
,
123
]. For example, Ding Yan et al. developed a HPLC method to determine the content
of eight pharmacological compounds, namely, gallic acid (
97
), paeoniflorin (
12
), galloylpaeoniflorin
(
15
), benzoic acid (
104
), quercetin (
63
), benzoylpaeoniflorin (
17
), paeoniflorigenone (
1
), and paeonol
(
83
) [
124
]. This method was achieved on C18 column by gradient elution with 0.05% formic acid in
water and acetonitrile. The method validation gave acceptable linearities (r= 0.9996) and recoveries
(ranging from 99.4–103.1%). The limits of detection (LOD) of these compounds ranged from 10 to
30 µg/mL.
For the analysis of natural products, chromatographic fingerprint (CFP) techniques, introduced
by the World Health Organization (WHO), provide a comprehensive approach that aims to assess the
quality of Chinese herbs and their finished products. CM, Radix Paeoniae Alba,Radix Paeoniae Rubra are
important Chinese herbs with similar bioactivities and efficacies. He Chunnian et al. established a
HPLC fingerprint method for the quality control of Radix Paeonia Alba,Radix Paeonia Rubra, and CM,
and to compare their main constituents. Eleven chromatographic peaks were identified and differences
of chromatographic peaks among these three herbal medicines in chemical compositions were
revealed [
125
]. As we know, due to the different growth environment as well as the processing method,
main ingredients contained in CM vary vastly. Wu Meizhen et al. determined chromatographic
fingerprints of P. suffruticosa by HPLC and applied the clustering analysis for data processing [
126
].
Results suggest that the quantitative differences among different growing areas could be used to
classify herbals from different growing areas, while there seemed to be no quantitative differences for
processing factor. Hu Yunfei et al. establish and compare UPLC fingerprint of CM before and after

Molecules 2017,22, 946 14 of 27
stir-frying, the results show significant differences between fingerprints of CM and charred CM, in
which the contents of 5-hydroxymethyl furfural and paeoniflorin (
12
) changed dramatically [
127
]. This
method can reflect the differences of component before and after stir-frying quickly and effectively,
and provides the scientific basis for processing technology and quality evaluation of CM. To obtain
the characteristic chromatographic profiles of CM, Fan Xuhang et al. developed a UPLC method that
determine fifteen batches of CM on an HSS T3 column (2.1 mm
×
100 mm, 1.8
µ
m) eluted with the
mobile phase consisted of water containing 0.05% phosphoric acid and acetonitrile in gradient mode
with detection wavelength set at 254 nm [
128
]. The results indicate there were 20 common peaks in
the characteristic chromatographic profile of 15 samples, 10 of which were identified, and the similar
degrees of the fifteen batches to the common mode were between 0.973–0.998.
Currently, HPLC remains the dominant analytical methods in the routine qualitative or
quantitative analysis of CM, due to high reproducibility and sensitivity, good linearity and relatively
inexpensive instrument.
5.2.3. LC-MS Analysis
LC-MS has been a powerful analytical tool for the rapid identification of chemical constituents
in herbal medicine. It combined the separation of HPLC and the structure information provided
by MS which is extremely advantageous in the analysis of complex herbal matrix compared with
the conventional arduous and time-consuming phytochemical techniques. Besides, there are some
compounds with no UV absorption in CM, such as terpenoids, steroids, fatty acids and sugars,
MS detector may be good options for the analysis of these compounds [
129
]. Meanwhile, high
resolution MS, like quadruple time-of-flight mass spectrometry (QTOF-MS), deliver a powerful tool
for identification of analytes and mass measurements. HPLC coupled with QTOF-MS can provide
valuable information to rapidly quantify the potential chemical markers for herbs with similar chemical
characteristics, such as albiflorin (
14
), paeoniflorin (
12
), oxypaeoniflorin (
13
), benzoylpaeoniflorin
(
17
), galloylalbiflorin (
15
) and paeoniflorigenone (
1
) [
130
]. For example, He Qing et al. reported a
HPLC-DAD-ESI/MS
n
method which identify seventeen peaks by their characteristic UV profile and the
information of molecular structure provided by ESI/MS
n
experiments while simultaneously determine
five key pharmacological compouds, namely gallic acid (
97
), oxypaeoniflorin (
13
), paeoniflorin (
12
),
benzoylpaeoniflorin (
17
), and paeonol (
83
), by the validated HPLC-DAD method. This method, with
good linearity, precision and recoveries, combined the chromatographic fingerprints and quantification
assay [
131
]. In addition, capillary high performance liquid chromatography coupled with electrospray
ionization mass spectrometry was reported to rapidly analyze pinnae monoterpene glycosides in
CM [132].
LC-MS was usually employed to differentiate CM with different processing methods or from
different regions and authenticate CM from substitute drugs. Deng Xianmei et al. established
a HPLC-DAD-ESIMS method to study the difference of chemical composition between raw and
processed CM. Significant changes in their chemical compositions before and after stir-frying processed
were detected, which may explain the different medicinal properties of raw and processed CM [
133
].
Besides, in the sulfur-fumigated CM, the amount of sulfur dioxide was significantly decreased,
while sulfur-containing markers, oxypaeoniflorin sulfonate and benzoylpaeoniflorin sulfonate, were
not decreased after eight-month storage. Therefore, sulfur dioxide residue index alone may not
objectively reflect the sulfur-fumigation extent (quality change extent) of CM. Hence, a more specific
method using characteristic sulfur-containing derivatives as chemical makers should be developed
to supplement the sulfur dioxide residue determination in the quality control of sulfur-fumigated
CM [
134
]. Again, in some regions, such as Yunnan and Sichuan Provinces in China, root cortex of
P. delavayi and P. decomposita also are used under the name of P. suffruticosa. To characterize and
differentiate these three species, Xu Shunjun et al. make a comparison of their chemical constituents
by HPLC-DAD/ESI-MS
2
. The large differences in chemical compounds among the three Paeonia

Molecules 2017,22, 946 15 of 27
species indicate that galloylglucose and acetophenone patterns could be used as taxonomic markers to
differentiate these three Paeonia species [121].
As we know, LDP in Chinese pharmacopeia was assessed by the content of two active compounds,
paeonol (
83
) from CM and loganin from Cornus officinalis, but content determination of only two active
compounds cannot fully reflect the holistic quality of LDP. There are many articles reporting HPLC
fingerprint of LDP condensed pills, but few articles have identified the common chromatographic peaks
due to lack of reference standards. In a recent study, Q-TOF-MS-IDA-MS/MS method was employed
for the qualitative determination of eighteen chromatographic peaks without reference standards.
By comparing the HPLC chromatographic fingerprints of LDP condensed pills and CM extract,
it is confirmed that paeonol (
83
), paeoniflorin (
12
). mudanpioside C (
20
) and oxypaeoniflorin (
8
),
galloylpaeoniflorin (15), benzoylpaeoniflorin contained in LDP condensed pills come from CM [135].
Metabolomics was initially proposed as a powerful approach for comprehensively profiling
endogenous metabolites at a cellular or organ level [
136
]. LC-MS based metabolomics approaches
are being successfully employed in many evaluations of the holistic quality of medicinal herbs.
UPLC-QTOF-MS based metabolomics coupled with characteristic ion exploration, a novel and
practical strategy was proposed for the rapid evaluation of holistic quality variations caused by
the sulfur-fumigation of CM [
137
]. The results suggested that sulfur-fumigation could significantly
affect the holistic quality of CM by chemically transforming pinane monoterpene glucosides, the main
bioactive components of CM, to their corresponding sulfonate derivatives. Similarly, Xiao Chaoni et
al. proposed a HPLC–MS method to gain deeper insights for revealing metabolomic variations in
different root parts of CM in order to enable quality control [
138
]. The results suggested that the axial
roots have higher quality than the lateral roots in CM due to the accumulation of bioactive secondary
metabolites associated with plant physiology. Liu Jianhua et al. [
139
] established a method which
combined serum pharmacochemistry with multiple data processing approach to screen the bioactive
components and their metabolites in CM by UPLC-MS. The results, obtained from a comprehensive
comparative analysis of the fingerprints of the CM and its metabolic fingerprints in rat biological
samples, indicated that 23 components in the CM were absorbed into the rat body. In addition, only
seven components were found in the metabolic fingerprints, which suggested that they might be
metabolites of some components in the CM.
5.2.4. GC Analysis
GC and GC-MS are unanimously accepted methods for the analysis of volatile constituents of
TCMs, due to their sensitivity, stability and high efficiency [
140
]. To analyze the constituents of CM
methanol extract from five growing areas (Tongling, Bozhou, Diangjiang, Yuncheng and Jiaxing),
GC-MS and NIST05 database were used to analyze the constituents of CM extract, then the result was
verified by principal components analysis (PCA) and partial least squares and discriminant analysis
(PLS-DA) [
141
]. Forty-one constituents were identified in CM extract, 21 of which were common
constituents. Among them, aromatic and fatty acid compounds were main constituents, accounting
for more than 80% of the total extract. In addition, there were some differences in the relative contents
and types of chemical constituents of CM from different growing areas.
5.2.5. CE Analysis
Capillary electrophoresis is increasingly important for the quality control of herbal drugs due to its
minimum sample and solvents consumption, short analysis time and high separation efficiency [
142
].
Recent years, the application of CE on the analysis of herbal medicines has become an active area
of study. CM contains a series of water-soluble tannins. Wu Yating et al. develop a rapid and
efficient method based on HPLC and CE, using a phosphate eluent and a 5C18-MS separating column,
successfully analyze eight tannins at detection wavelength of 280 nm. The detection limit for the
marker substances varied from 0.04 to 0.93
µ
g/mL for the HPLC method and 0.02 to 0.36
µ
g/mL
for the CE method [
143
]. Furthermore, micellar electrokinetic capillary chromatography (MEKC) is

Molecules 2017,22, 946 16 of 27
a well-established separation mode of CE. The merit of HPLC is also emerged in MEKC, which is
particularly useful for the analysis of complex mixture. MEKC and LC were applied to determine
paeonol (
83
) and paeoniflorin (
12
) in CM respectively. The optimized buffer system containing 10 mM
borate and 25 mM SDS at pH 9.5 were employed. Good linear behavior was exhibited over the
investigated concentration range. It was shown that no significant difference was found in the analysis
of CM by the developed MEKC and HPLC methods [144].
Electrochemical detection (ECD) typically operated in the amperometric mode can be coupled with
CE to provide high sensitivity and selectivity for the determination of electro-active substances [
145
].
Chen Gang et al. establish a method based on capillary electrophoresis with electrochemical detection
for the separation and determination of paeoniflorin (
12
), sucrose, paeonoside (
84
), glucose, and
fructose in CM [
146
,
147
]. As the primary metabolites, sucrose, glucose, and fructose are found widely
presented in plants and higher contents of sugars can indicate the better quality of some herbal
drugs [
148
]. This CE-ECD method is characterized by its higher resolution and sensitivity, lower
expense of operation and less amount of sample. Besides, the main advantage of CE as an analytical
technique for the analysis of plant samples is that the capillary is much easier to wash.
5.2.6. Spectrometric Methods and Others
Recently, quantitative
1
H-NMR (
1
H-qNMR) was applied to the determination of paeonol (
83
)
concentration in CM, Hachimijiogan, and Keishibukuryogan [
149
]. The
1
H-qNMR method has many
advantages, it requires neither reference compounds for establishing calibration curves nor sample
pre-purification, but it is limited by its inherent low sensitivity. NMR was employed to determine the
distribution of metabolites in the root bark of different tree peony cultivars for quality assessment.
Sixteen metabolites including sucrose, acetophenones, phenols, monoterpene glycosides, flavonoids
and unsaturated fatty acids were simultaneously identified and quantified [
150
]. Besides, to identify
three different samples, CM in Tongling, Luoyang and P. lactifloral pall in Hanzhou, Fourier transform
infrared (FTIR) spectroscopy combined with second derivative spectra and two-dimensional correlation
infrared spectroscopy was applied [
151
]. Significant difference was found in the two-dimensional
spectra in the range of 1730~1380 cm
−1
and 1000~500 cm
−1
within the three samples. This result
suggests that FTIR combined with 2D correlation IR can be successfully and rapidly applied to
distinguish CM among different geographical regions.
Yang Suling et al. developed a simple, highly sensitive method using modified glassy carbon
electrode with Nafion/multi-wall carbon nanotubes as a sensitive voltammetric sensor to determine
the content of paeonol (
83
) in several pharmaceutical and biological samples, including CM, LDP and
paeonol (
83
) spiked LDP, urine, and plasma samples [
152
]. This modified electrode was characterized
by spaghetti-like porous surface, and it significantly increased the oxidation peak current of paeonol
(
83
) while reducing the oxidation potential. This method could be successfully applied to the
quantification of paeonol (
83
) in drug and biological samples. Papers were published recently about
quantum dots (QDs) based fluorescence quenching method to determine constituents like paeonol
(83) and paeoniflorin (12). Semiconductors QDs are used as fluorescence nanosensor because of their
high chemical stability and photoluminescence quantum yield. Aqueous polymethylmethacrylate
(PMMA)-capped CdSe/ZnS quantum dots were used as fluorescence probes for paeonol (
83
)
determination [
153
]. Additionally, water soluble ZnSe QDs modified by mercaptoacetic acid were used
to determinate paeoniflorin (
12
) in aqueous solutions by the fluorescence spectroscopic technique [
154
].
Compared with the CdSe/ZnS QDs, ZnSe QDs can be directly and simply synthesized in a water-phase
system, and the synthetic process is more reproducible and cost effective, and less expensive and toxic.
Besides, Jiang Lei et al. detected the contents of inorganic elements in 15 batches of P. suffruticosa
from different origins, the result showed that the main elements in CM were lithium, zinc, lead,
iron and potassium: the contents of inorganic elements in P. suffruticosa daodi and non-daodi regional
drug showed certain differences [
155
]. The intricate relationship between therapeutic effects of CM
and the morphological and dissolution characteristics of various trace elements in CM need further

Molecules 2017,22, 946 17 of 27
investigation [
156
]. Also, chemical analysis of CM was investigated, including the organic components
assaying using HPLC and the trace metal elements determination by ICP-MS. The results suggested
that the essential metals as well as some metallic pollutants were related to the organic compounds on
the basis of their concentrations. This suggests the close relationship between organic and inorganic
compounds [
157
]. Given the special effects of trace elements on the quality of CM, it is suggested
that the trace element should be considered and included when establishing chemical fingerprints of
CM [158].
In comparison, TLC analysis allows authentication of peonies in a simple, inexpensive and
unambiguous way, but TLC was less accurate and often showed less reproducible result between
inter-laboratory results. For multi-component quantitative analysis of CM, HPLC and hyphenated
techniques are dominant method to be routinely conducted for analyzing CM, due to its easy operation,
wide suitability and high accuracy characteristics. GC was usually employed to detect the volatile
components, like paeonol (
83
), and pesticide residue in CM. CE showed higher resolution and
sensitivity compared to HPLC but displayed poor reproducibility. LC-MS is not only a good choice for
identification of unknown compounds but also proper for quantitative analysis with high sensitivity.
LC-MS is widely employed to study the chemical profiling of CM in pharmacokinetic studies and
in vivo
metabolomics research. However, LC-MS is currently still confined to an area of research due
to expensive instruments. Spectrometric methods, such as NMR, can provide structural information,
so NMR can be a good option with the absence of reference standard. Besides, other methods, like
QDs, provide good alternatives in the quality evaluation of CM.
6. Safety
CM, as a commonly used TCM, was generally considered safe and showed few adverse drug
effects in the clinic use during long history. CM does not contain obvious toxic ingredients [
159
]
except benzoic acid (
104
). Benzoic acid (
104
) was considered to be harmful constituent, but the
content of benzoic acid in CM is very low [
160
]. Moreover, no clinical or biochemical evidence of
adverse drug reaction concerning CM was found during literature retrieval. However, TCMs are
easily contaminated with heavy metal through polluted soils, irrigation waters, atmospheric dusts,
automobile and industrial exhausts, as well as pesticides and fertilizers [
161
]. Despite its innate safety,
CM may be contaminated by exogenous harmful substances, like heavy metals, pesticide residue,
or excess in sulfur content by sulfur fumigation. A method combining gas chromatography and matrix
solid-phase dispersion was proposed to simultaneously determine 11 pesticide residues in CM, such
as organochlorines and pyrethroid [162].
As we know, trace elements play an important role in plant growth and formation of active
chemical constituents. It is reported that Cu in soil enhances paeonol (
83
) accumulation in CM of
P. suffruticosa “Fengdan” [
163
]. However, some heavy metals (zinc, iron, copper, chromium, and cobalt)
may be beneficial at low concentration and become toxic at high concentration, while others (lead
and cadmium) have no known beneficial properties and are hence exclusively toxic [
164
]. Therefore,
determinations of trace elements in CM are crucial for understanding the nutritive importance of some
elements (Fe, Zn, Cu, Mn) and quality assurance of CM [
165
]. Chinese Pharmacopoeia (2015 edition)
did not specify the determination of heavy metals and other harmful elements, but several researches
detected the existence of heavy metals in CM [
166
]. Planting soil of CM in different producing areas was
rich in lead and cadmium, and it is essential to protect planting soil from heavy metal pollution [
167
].
7. Conclusions
TCMs are invaluable resources for new drug discovery, and they are drawing more and more
attention worldwide by virtue of their specific theory and long historical clinical practice [
140
]. CM,
as one of the commonly used TCMs, plays important roles in TCM formula or prescription, like LDP,
Shuangdan Capsule, Guizhi Fuling Pills, etc. However, unmanageable quality is the bottleneck for its
modernization and globalization.

Molecules 2017,22, 946 18 of 27
It is now commonly believed that TCMs owe their biological activities to the synergistic effects of
all the major and minor components in the medicine. One hundred and nineteen compounds were
found from CM, which can be assigned to seven classes: monoterpenes, monoterpene glycosides,
flavonoids, tannins, triterpenoids, phenols and others. Many of them are proven to be effective for
certain diseases or protein targets, this contributes to the wide range of pharmacological effects of
CM, anti-oxidant, anti-inflammatory, anti-tumor, etc. The various structurally complex metabolites in
CM might be promising candidates for lead compounds in new drug development. Moreover, omics
methods, like proteomics and metabolomics, and network pharmcology investigations of CM should
be conducted to unravel the pharmacological mechanisms of CM involving multi-components and
multi-targets [168].
Various analytical methods, such as HPLC, CE and LC-MS are capable of determining the
content of paeonol (
83
), paeonoflorin (
12
) and other compounds, and simultaneously obtaining
chromatographic fingerprints of CM. These methods were used to evaluate CM herb from different
localities and pharmaceutical manufacturers [
169
,
170
]. However, these analytical methods still need to
be further improved and optimized to acquire a robust, comprehensive, rapid, applicable analytical
approach for quality evaluation of CM. Quality criteria of CM in different countries and areas need to be
improved in order to obtain a more harmonized quality standard. Selection of reference substances is
the key point for quality evaluation of herbal products and simultaneous monitoring of multiple
components has become a tendency nowadays [
171
]. Current criteria for CM only include the
determination of certain selected constituents of higher content, such as paeonol (
83
) and paeoniflorin
(
12
). Some bioactive compounds, such as gallic acid (
97
), paeoniflorin (
12
), benzoylpaeoniflorin (
17
),
α
-benzoyloxypaeoniflorin (
28
), benzoic acid (
104
) and quercetin (
63
) are frequently chosen to be
marker compounds in the authentication and quality evaluation of CM. These compounds should be
considered to be new chemical markers in the quality criteria of CM due to their potent pharmacological
effects and relatively high contents in CM.
Supplementary Materials: Supplementary materials are available online.
Acknowledgments:
This work would not be accomplished without the support from Special Fund for TCM by
State Administration of Traditional Chinese Medicine of China (Grant NO. 201507002-10), the CAMS Innovation
Fund for Medical Sciences (CIFMS) ID: 2016-I2M-1-012, and the National Standardization Program for Chinese
Medicine-“Construction of Liuwei Dihuang Capsule Standard” (Grant NO.: ZYBZH-C-JL-24).
Author Contributions:
The manuscript was conceived by all authors. Feihu Chen, Chunnian He designed the
review, Zhiqiang Wang drafted the manuscript which was subsequently edited by Yong Peng and Peigen Xiao.
Conflicts of Interest:
We wish to confirm that there are no known conflicts of interest associated with
this publication.
References
1.
Chinese Pharmacopeia Commission. Pharmacopoeia of the People’s Republic of China, English Edition; People’s
Medical Publishing House: Beijing, China, 2015; Volume I.
2.
Fu, P.K.; Yang, C.Y.; Tsai, T.H.; Hsieh, C.L. Moutan cortex radicis improves lipopolysaccharide-induced acute
lung injury in rats through anti-inflammation. Phytomedicine 2012,19, 1206–1215. [CrossRef] [PubMed]
3. Lim, T.K. Edible Medicinal and Non-Medicinal Plants; Springer: New York, NY, USA, 2012; Volume 8.
4.
List of Kampo Herbs. Available online: http://en.wikipedia.org/wiki/List_of_kampo_herbs (accessed on
5 June 2017).
5.
Matsuda, H.; Ohta, T.; Kawaguchi, A.; Yoshikawa, M. Bioactive constituents of chinese natural medicines.
VI. Moutan cortex. (2): Structures and radical scavenging effects of suffruticosides A, B, C, D, and E and
galloyl-oxypaeoniflorin. Chem. Pharm. Bull. 2001,49, 69–72. [CrossRef] [PubMed]
6.
Yoshikawa, M.; Uchida, E.; Kawaguchi, A.; Kitagawa, I.; Yamahara, J. Galloyl-oxypaeoniflorin, suffruticosides
A, B, C, and D, five new antioxidative glycosides, and suffruticoside e, a paeonol glycoside, from chinese
moutan cortex. Chem. Pharm. Bull. 1992,40, 2248–2250. [CrossRef] [PubMed]
7.
Wu, M.; Gu, Z. Screening of bioactive compounds from moutan cortex and their anti-inflammatory activities
in rat synoviocytes. Evid.-Based Complement. Altern. Med. 2009,6, 57–63. [CrossRef] [PubMed]

Molecules 2017,22, 946 19 of 27
8.
Yun, C.S.; Choi, Y.G.; Jeong, M.Y.; Lee, J.H.; Lim, S. Moutan cortex radicis inhibits inflammatory changes
of gene expression in lipopolysaccharide-stimulated gingival fibroblasts. J. Nat. Med.
2013
,67, 576–589.
[CrossRef] [PubMed]
9.
Jiang, S.; Nakano, Y.; Yatsuzuka, R.; Ono, R.; Kamei, C. Inhibitory effects of moutan cortex on immediate
allergic reactions. Biol. Pharm. Bull. 2007,30, 1707–1710. [CrossRef] [PubMed]
10.
Liu, K.Y.; Hu, S.; Chan, B.C.; Wat, E.C.; Lau, C.; Hon, K.L.; Fung, K.P.; Leung, P.C.; Hui, P.C.; Lam, C.W.
Anti-inflammatory and anti-allergic activities of pentaherb formula, moutan cortex (danpi) and gallic acid.
Molecules (Basel Switzerland) 2013,18, 2483–2500. [CrossRef] [PubMed]
11.
Rho, S.; Chung, H.S.; Kang, M.; Lee, E.; Cho, C.; Kim, H.; Park, S.; Kim, H.Y.; Hong, M.; Shin, M. Inhibition of
production of reactive oxygen species and gene expression profile by treatment of ethanol extract of moutan
cortex radicis in oxidative stressed pc12 cells. Biol. Pharm. Bull. 2005,28, 661–666. [CrossRef] [PubMed]
12.
Zhang, M.; Feng, L.; Gu, J.; Ma, L.; Qin, D.; Wu, C.; Jia, X. The attenuation of moutan cortex on oxidative
stress for renal injury in ages-induced mesangial cell dysfunction and streptozotocin-induced diabetic
nephropathy rats. Oxid. Med. Cell. Longev. 2014,2014, 463815. [CrossRef] [PubMed]
13.
Lan, B.; Li, J.; Duan, Q. An Encyclopedia of the Tree Peonies in China; China Science and Technology Press:
Beijing, China, 2002.
14.
Zhang, J.; Wang, J.; Xia, T.; Zhou, S. DNA barcoding: Species delimitation in tree peonies. Sci. China Ser. C
Life Sci. 2009,52, 568–578. [CrossRef] [PubMed]
15.
He, C.; Peng, B.; Dan, Y.; Peng, Y.; Xiao, P. Chemical taxonomy of tree peony species from china based on
root cortex metabolic fingerprinting. Phytochemistry 2014,107, 69–79. [CrossRef] [PubMed]
16.
Ha, D.T.; Ngoc, T.M.; Lee, I.; Lee, Y.M.; Kim, J.S.; Jung, H.; Lee, S.; Na, M.; Bae, K. Inhibitors of aldose reductase
and formation of advanced glycation end-products in moutan cortex (Paeonia suffruticosa). J. Nat. Prod.
2009
,
72, 1465–1470. [CrossRef] [PubMed]
17.
Ding, L.; Jiang, Z.; Liu, Y.; Chen, L.; Zhao, Q.; Yao, X.; Zhao, F.; Qiu, F. Monoterpenoid inhibitors of no
production from Paeonia suffruticosa.Fitoterapia 2012,83, 1598–1603. [CrossRef] [PubMed]
18.
Ding, L.; Zhao, F.; Chen, L.; Jiang, Z.; Liu, Y.; Li, Z.; Qiu, F.; Yao, X. New monoterpene glycosides from
Paeonia suffruticosa andrews and their inhibition on NO production in LPS-induced RAW 264.7 cells.
Bioorg. Med. Chem. Lett. 2012,22, 7243–7247. [CrossRef] [PubMed]
19.
Wu, S.H.; Wu, D.G.; Chen, Y.W. Chemical constituents and bioactivities of plants from the genus paeonia.
Chem. Biodivers. 2010,7, 90–104. [CrossRef] [PubMed]
20.
Ding, H.Y.; Wu, Y.C.; Lin, H.C.; Chan, Y.Y.; Wu, P.L.; Wu, T.S. Glycosides from Paeonia suffruticosa.
Chem. Pharm. Bull. 1999,47, 652–655. [CrossRef]
21.
Zhou, S.L.; Zou, X.H.; Zhou, Z.Q.; Liu, J.; Xu, C.; Yu, J.; Wang, Q.; Zhang, D.M.; Wang, X.Q.; Ge, S. Multiple
species of wild tree peonies gave rise to the ‘king of flowers’, Paeonia suffruticosa andrews. Proc. R. Soc. Lond.
B Biol. Sci. 2014,281, 20141687. [CrossRef] [PubMed]
22.
An, R.B.; Kim, H.C.; Lee, S.H.; Jeong, G.S.; Sohn, D.H.; Park, H.; Kwon, D.Y.; Lee, J.H.; Kim, Y.C. A new
monoterpene glycoside and antibacterial monoterpene glycosides from Paeonia suffruticosa.Arch. Pharm. Res.
2006,29, 815. [CrossRef] [PubMed]
23.
Yang, Y.; Hu, H.Y.; Yu, N.J.; Zhang, Y.; Zhao, Y.M. Three new paeonidanin—Type monoterpene glycosides
from Paeonia suffruticosa andr. Helv. Chim. Acta 2010,93, 1622–1627. [CrossRef]
24.
Song, W.H.; Cheng, Z.H.; Chen, D.F. Anticomplement monoterpenoid glucosides from the root bark of
Paeonia suffruticosa.J. Nat. Prod. 2013,77, 42–48. [CrossRef] [PubMed]
25.
Li, G.; Seo, C.S.; Lee, K.S.; Kim, H.J.; Chang, H.W.; Jung, J.S.; Song, D.K.; Son, J.K. Protective constituents
against sepsis in mice from the root cortex of Paeonia suffruticosa.Arch. Pharm. Res.
2004
,27, 1123–1126.
[CrossRef] [PubMed]
26.
Lin, H.C.; Ding, H.Y.; Wu, Y.C. Two novel compounds from Paeonia suffruticosa.J. Nat. Prod.
1998
,61, 343–346.
[CrossRef] [PubMed]
27.
Choi, Y.H.; Yoo, H.J.; Noh, I.C.; Lee, J.M.; Park, J.W.; Choi, W.S.; Choi, J.H. Bioassay-guided isolation of novel
compound from Paeonia suffruticosa andrews roots as an IL-1
β
inhibitor. Arch. Pharm. Res.
2012
,35, 801–805.
[CrossRef] [PubMed]
28.
Wang, S.; Yang, Y.; Li, S.; Shi, J. A new paeoniflorin derivative isolated from the root bark ethanol extract of
Paeonia suffruticosa.Zhongguo Zhong Yao Za Zhi 2005,30, 759–761. [PubMed]

Molecules 2017,22, 946 20 of 27
29.
Yoshikawa, M.; Harada, E.; Minematsu, T.; Muraoka, O.; Yamahara, J.; Murakami, N.; Kitagawa, I. Absolute
stereostructures of paeonisothujone, a novel skeletal monoterpene ketone, and deoxypaeonisuffrone, and
isopaeonisuffral, two new monoterpenes, from moutan cortex. Chem. Pharm. Bull.
1994
,42, 736–738.
[CrossRef]
30.
Yoshikawa, M.; Ohta, T.; Kawaguchi, A.; Matsuda, H. Bioactive constituents of chinese natural medicines.
V. Radical scavenging effect of moutan cortex. (1): Absolute stereostructures of two monoterpenes,
paeonisuffrone and paeonisuffral. Chem. Pharm. Bull. 2000,48, 1327–1331. [CrossRef] [PubMed]
31.
He, C.N.; Peng, Y.; Zhang, Y.C.; Xu, L.J.; Gu, J.; Xiao, P.G. Phytochemical and biological studies of paeoniaceae.
Chem. Biodivers. 2010,7, 805–838. [CrossRef] [PubMed]
32.
Lin, H.C.; Ding, H.Y.; Wu, T.S.; Wu, P.L. Monoterpene glycosides from Paeonia suffruticosa.Phytochemistry
1996,41, 237–242.
33.
Zhu, X.; Fang, Z.H. New monoterpene glycosides from the root cortex of Paeonia suffruticosa and their
potential anti-inflammatory activity. Nat. Prod. Res. 2014,28, 301–305. [CrossRef] [PubMed]
34.
Furuya, R.; Hu, H.; Zhang, Z.; Shigemori, H. Suffruyabiosides a and b, two new monoterpene diglycosides
from moutan cortex. Molecules (Basel, Switzerland) 2012,17, 4915–4923. [CrossRef] [PubMed]
35.
Lee, S.J.; Lee, I.S.; Mar, W. Inhibition of inducible nitric oxide synthase and cyclooxygenase-2 activity by
1,2,3,4,6-penta-O-galloyl-
β
-D-glucose in murine macrophage cells. Arch. Pharm. Res.
2003
,26, 832–839.
[CrossRef] [PubMed]
36.
Satoh, K.; Nagai, F.; Ushiyama, K.; Yasuda, I.; Seto, T.; Kano, I. Inhibition of Na
+
, K
+
-atpase by
1,2,3,4,6-penta-O-galloyl-
β
-D-glucose, a major constituent of both moutan cortex and paeoniae radix.
Biochem. Pharmacol. 1997,53, 611–614. [CrossRef]
37.
Wang, R.; Lechtenberg, M.; Sendker, J.; Petereit, F.; Deters, A.; Hensel, A. Wound-healing plants from
tcm:
In vitro
investigations on selected TCM plants and their influence on human dermal fibroblasts and
keratinocytes. Fitoterapia 2013,84, 308–317. [CrossRef] [PubMed]
38.
Ding, L.; Zuo, Q.; Li, D.; Feng, X.; Gao, X.; Zhao, F.; Qiu, F. A new phenone from the roots of Paeonia suffruticosa
andrews. Nat. Prod. Res. 2017,31, 253–260. [CrossRef] [PubMed]
39.
Xiao, K.; Song, Q.H.; Zhang, S.-W.; Xuan, L.J. A pyrrole derivative from Paeonia suffruticosa.Nat. Prod. Res.
2008,22, 1614–1619. [CrossRef] [PubMed]
40.
Li, H.B.; Wong, C.C.; Cheng, K.W.; Chen, F. Antioxidant properties
in vitro
and total phenolic contents in
methanol extracts from medicinal plants. LWT-Food Sci. Technol. 2008,41, 385–390. [CrossRef]
41.
Li, H.; Xie, Y.H.; Yang, Q.; Wang, S.W.; Zhang, B.L.; Wang, J.B.; Cao, W.; Bi, L.L.; Sun, J.Y.; Miao, S.
Cardioprotective effect of paeonol and danshensu combination on isoproterenol-induced myocardial injury
in rats. PLoS ONE 2012,7, e48872. [CrossRef] [PubMed]
42.
Liu, M.H.; Lin, A.H.; Lee, H.F.; Ko, H.K.; Lee, T.S.; Kou, Y.R. Paeonol attenuates cigarette smoke-induced
lung inflammation by inhibiting ros-sensitive inflammatory signaling. Mediat. Inflamm.
2014
,2014, 651890.
[CrossRef] [PubMed]
43.
Li, C.R.; Zhou, Z.; Zhu, D.; Sun, Y.N.; Dai, J.M.; Wang, S.Q. Protective effect of paeoniflorin on
irradiation-induced cell damage involved in modulation of reactive oxygen species and the mitogen-activated
protein kinases. Int. J. Biochem. Cell Biol. 2007,39, 426–438. [CrossRef] [PubMed]
44.
Yu, J.; Zhu, X.; Qi, X.; Che, J.; Cao, B. Paeoniflorin protects human ea. Hy926 endothelial cells against
gamma-radiation induced oxidative injury by activating the NF-E2-related factor 2/heme oxygenase-1
pathway. Toxicol. Lett. 2013,218, 224–234. [CrossRef] [PubMed]
45.
Xie, W.; Yu, W.; Zhao, M.; Zhou, W.; Chen, H.; Du, W.; Huang, L.; Xu, Y.; Li, X. Protective effect of paeoniflorin
against oxidative stress in human retinal pigment epithelium in vitro. Mol. Vis. 2011,17, 3512–3533.
46.
Yao, C.W.; Piao, M.J.; Kim, K.C.; Zheng, J.; Cha, J.W.; Hyun, J.W. 6
0
-O-galloylpaeoniflorin protects human
keratinocytes against oxidative stress-induced cell damage. Biomol. Ther.
2013
,21, 349. [CrossRef] [PubMed]
47.
Chun, S.C.; Jee, S.Y.; Lee, S.G.; Park, S.J.; Lee, J.R.; Kim, S.C. Anti-inflammatory activity of the methanol
extract of moutan cortex in LPS-activated RAW264. 7 cells. Evid.-Based Complement. Altern. Med.
2007
,4,
327–333. [CrossRef] [PubMed]
48.
Huang, H.; Chang, E.; Lee, Y.; Kim, J.; Kang, S.; Kim, H. A genome-wide microarray analysis reveals
anti-inflammatory target genes of paeonol in macrophages. Inflamm. Res.
2008
,57, 189–198. [CrossRef]
[PubMed]

Molecules 2017,22, 946 21 of 27
49.
Li, J.Z.; Wu, J.H.; Yu, S.Y.; Shao, Q.R.; Dong, X.M. Inhibitory effects of paeoniflorin on
lysophosphatidylcholine-induced inflammatory factor production in human umbilical vein endothelial cells.
Int. J. Mol. Med. 2013,31, 493–497. [CrossRef] [PubMed]
50.
Oh, G.; Pae, H.; Choi, B.; Jeong, S.; Oh, H.; Oh, C.; Rho, Y.; Kim, D.; Shin, M.; Chung, H.-T. Inhibitory
effects of the root cortex of Paeonia suffruticosa on interleukin-8 and macrophage chemoattractant protein-1
secretions in U937 cells. J. Ethnopharmacol. 2003,84, 85–89. [CrossRef]
51.
Chen, N.; Liu, D.; Soromou, L.W.; Sun, J.; Zhong, W.; Guo, W.; Huo, M.; Li, H.; Guan, S.; Chen, Z. Paeonol
suppresses lipopolysaccharide—Induced inflammatory cytokines in macrophage cells and protects mice
from lethal endotoxin shock. Fundam. Clin. Pharmacol. 2014,28, 268–276. [CrossRef] [PubMed]
52.
Li, N.; Fan, L.L.; Sun, G.-P.; Wan, X.A.; Wang, Z.G.; Wu, Q.; Wang, H. Paeonol inhibits tumor growth in
gastric cancer in vitro and in vivo. World J. Gastroenterol. 2010,16, 4483–4490. [CrossRef] [PubMed]
53.
Sun, G.P.; Wan, X.; Xu, S.P.; Wang, H.; Liu, S.H.; Wang, Z.G. Antiproliferation and apoptosis induction of
paeonol in human esophageal cancer cell lines. Dis. Esophagus 2008,21, 723–729. [CrossRef] [PubMed]
54.
Lee, S.; Lee, H. Inhibitory effects of Paeonia suffruticosa andrews extracts on VEGF binding to vegf receptor.
Nat. Prod. Sci. 2007,13, 128.
55.
Lin, M.Y.; Shen, C.H.; Chiang, S.Y.; Chen, S.Y.; Lin, Y.S.; Hsu, C.D. Cortex moutan inhibits bladder cancer cell
proliferation and expression of angiogenic factors. Pharmacol. Pharm. 2014,5, 846–858. [CrossRef]
56.
Horng, C.T.; Shieh, P.C.; Tan, T.W.; Yang, W.H.; Tang, C.H. Paeonol suppresses chondrosarcoma metastasis
through up-regulation of miR-141 by modulating PKC
δ
and c-Src signaling pathway. Int. J. Mol. Sci.
2014
,
15, 11760–11772. [CrossRef] [PubMed]
57.
Zhang, L.; Tao, L.; Shi, T.; Zhang, F.; Sheng, X.; Cao, Y.; Zheng, S.; Wang, A.; Qian, W.; Jiang, L. Paeonol inhibits
B16F10 melanoma metastasis
in vitro
and
in vivo
via disrupting proinflammatory cytokines-mediated NF-
κ
B
and STAT3 pathways. IUBMB Life 2015,67, 778–788. [CrossRef] [PubMed]
58.
Xu, S.P.; Sun, G.P.; Shen, Y.X.; Wei, W.; Peng, W.R.; Wang, H. Antiproliferation and apoptosis induction of
paeonol in HepG2 cells. World J. Gastroenterol. 2007,13, 250. [CrossRef] [PubMed]
59.
Ou, Y.; Li, Q.; Wang, J.; Li, K.; Zhou, S. Antitumor and apoptosis induction effects of paeonol on mice bearing
EMT6 breast carcinoma. Biomol. Ther. 2014,22, 341–346. [CrossRef] [PubMed]
60.
Sun, G.P.; Wang, H.; Xu, S.P.; Shen, Y.X.; Wu, Q.; Chen, Z.D.; Wei, W. Anti-tumor effects of paeonol in a
hepa-hepatoma bearing mouse model via induction of tumor cell apoptosis and stimulation of IL-2 and
TNF-αproduction. Eur. J. Pharmacol. 2008,584, 246–252. [CrossRef] [PubMed]
61.
Cai, J.; Chen, S.; Zhang, W.; Hu, S.; Lu, J.; Xing, J.; Dong, Y. Paeonol reverses paclitaxel resistance in human
breast cancer cells by regulating the expression of transgelin 2. Phytomedicine
2014
,21, 984–991. [CrossRef]
[PubMed]
62.
Li, M.; Tan, S.-Y.; Wang, X.-F. Paeonol exerts an anticancer effect on human colorectal cancer cells through
inhibition of PGE2 synthesis and cox-2 expression. Oncol. Rep. 2014,32, 2845–2853. [CrossRef] [PubMed]
63.
Zhang, Q.; Yuan, Y.; Cui, J.; Xiao, T.; Jiang, D. Paeoniflorin inhibits proliferation and invasion of breast cancer
cells through suppressing Notch-1 signaling pathway. Biomed. Pharmacother.
2016
,78, 197–203. [CrossRef]
[PubMed]
64.
Wu, Q.; Chen, G.-L.; Li, Y.-J.; Chen, Y.; Lin, F.-Z. Paeoniflorin inhibits macrophage-mediated lung cancer
metastasis. Chin. J. Nat. Med. 2015,13, 925–932. [CrossRef]
65.
Li, W.; Qi, Z.; Wei, Z.; Liu, S.; Wang, P.; Chen, Y.; Zhao, Y. Paeoniflorin inhibits proliferation and
induces apoptosis of human glioma cells via microrna-16 upregulation and matrix metalloproteinase-9
downregulation. Mol. Med. Rep. 2015,12, 2735–2740. [CrossRef] [PubMed]
66.
Oh, G.S.; Pae, H.O.; Oh, H.; Hong, S.G.; Kim, I.K.; Chai, K.Y.; Yun, Y.G.; Kwon, T.O.; Chung, H.T.
In vitro
anti-proliferative effect of 1,2,3,4,6-penta-O-galloyl-
β
-D-glucose on human hepatocellular carcinoma cell
line, sk-hep-1 cells. Cancer Lett. 2001,174, 17–24. [CrossRef]
67.
Pan, J.Y.; Cheng, Y.Y. Identification and analysis of absorbed and metabolic components in rat plasma after
oral administration of ‘shuangdan’ granule by HPLC–DAD–ESI-MS/MS. J. Pharm. Biomed. Anal.
2006
,42,
565–572. [CrossRef] [PubMed]
68.
Dan, H.; Zhang, L.; Qin, X.; Peng, X.; Wong, M.; Tan, X.; Yu, S.; Fang, N. Moutan cortex extract exerts
protective effects in a rat model of cardiac ischemia/reperfusion. Can. J. Physiol. Pharmacol.
2015
,94, 245–250.
[CrossRef] [PubMed]

Molecules 2017,22, 946 22 of 27
69.
Ma, L.; Chuang, C.C.; Weng, W.; Zhao, L.; Zheng, Y.; Zhang, J.; Zuo, L. Paeonol protects rat heart by
improving regional blood perfusion during no-reflow. Front. Physiol. 2016,7, 1–10. [CrossRef] [PubMed]
70.
Li, Y.j.; Bao, J.X.; Xu, J.w.; Murad, F.; Bian, K. Vascular dilation by paeonol—A mechanism study.
Vasc. Pharmacol. 2010,53, 169–176. [CrossRef] [PubMed]
71.
Ye, S.; Liu, X.; Mao, B.; Yang, L.; Liu, N. Paeonol enhances thrombus recanalization by inducing vascular
endothelial growth factor 165 via ERK1/2 MAPK signaling pathway. Mol. Med. Rep.
2016
,13, 4853–4858.
[PubMed]
72.
Ye, S.; Mao, B.; Yang, L.; Fu, W.; Hou, J. Thrombosis recanalization by paeoniflorin through the upregulation
of urokinase-type plasminogen activator via the MAPK signaling pathway. Mol. Med. Rep.
2016
,13,
4593–4598. [CrossRef] [PubMed]
73.
Wang, Y.Q.; Dai, M.; Zhong, J.C.; Yin, D.K. Paeonol inhibits oxidized low density lipoprotein-induced
monocyte adhesion to vascular endothelial cells by inhibiting the mitogen activated protein kinase pathway.
Biol. Pharm. Bull. 2012,35, 767–772. [CrossRef] [PubMed]
74.
Chen, C.; Du, P.; Wang, J. Paeoniflorin ameliorates acute myocardial infarction of rats by inhibiting
inflammation and inducible nitric oxide synthase signaling pathways. Mol. Med. Rep.
2015
,12, 3937–3943.
[PubMed]
75.
Chen, T.; Guo, Z.P.; Wang, L.; Qin, S.; Cao, N.; Li, M.m.; Jia, R.Z.; Wang, T.T. Paeoniflorin suppresses vascular
damage and the expression of E-selectin and ICAM-1 in a mouse model of cutaneous arthus reaction.
Exp. Dermatol. 2013,22, 453–457. [CrossRef] [PubMed]
76.
Koo, Y.K.; Kim, J.M.; Koo, J.Y.; Kang, S.S.; Bae, K.; Kim, Y.S.; Chung, J.-H.; Yun-Choi, H.S. Platelet
anti-aggregatory and blood anti-coagulant effects of compounds isolated from Paeonia lactiflora and
Paeonia suffruticosa.Die Pharm. Int. J. Pharm. Sci. 2010,65, 624–628.
77.
Hsu, P.C.; Tsai, Y.T.; Lai, J.N.; Wu, C.T.; Lin, S.K.; Huang, C.Y. Integrating traditional chinese medicine
healthcare into diabetes care by reducing the risk of developing kidney failure among type 2 diabetic
patients: A population-based case control study. J. Ethnopharmacol.
2014
,156, 358–364. [CrossRef] [PubMed]
78.
Zhang, M.H.; Feng, L.; Zhu, M.M.; Gu, J.F.; Jiang, J.; Cheng, X.D.; Ding, S.M.; Wu, C.; Jia, X.B.
The anti-inflammation effect of moutan cortex on advanced glycation end products-induced rat mesangial
cells dysfunction and high-glucose-fat diet and streptozotocin-induced diabetic nephropathy rats.
J. Ethnopharmacol. 2014,151, 591–600. [CrossRef] [PubMed]
79.
Lau, C.; Chan, C.; Chan, Y.; Lau, K.; Lau, T.; Lam, F.; Law, W.; Che, C.; Leung, P.; Fung, K. Pharmacological
investigations of the anti-diabetic effect of cortex moutan and its active component paeonol. Phytomedicine
2007,14, 778–784. [CrossRef] [PubMed]
80.
Liu, J.; Wang, S.; Feng, L.; Ma, D.; Fu, Q.; Song, Y.; Jia, X.; Ma, S. Hypoglycemic and antioxidant activities
of paeonol and its beneficial effect on diabetic encephalopathy in streptozotocin-induced diabetic rats.
J. Med. Food 2013,16, 577–586. [CrossRef] [PubMed]
81.
Fu, J.; Li, Y.; Wang, L.; Gao, B.; Zhang, N.; Ji, Q. Paeoniflorin prevents diabetic nephropathy in rats. Comp. Med.
2009,59, 557–566. [PubMed]
82.
Tuan, D.T.; Thu, N.B.; Nhiem, N.X.; Ngoc, T.M.; Yim, N.; Bae, K. Palbinone and triterpenes from moutan
cortex (Paeonia suffruticosa, paeoniaceae) stimulate glucose uptake and glycogen synthesis via activation of
AMPK in insulin-resistant human HepG2 cells. Bioorg. Med. Chem. Lett. 2009,19, 5556–5559.
83. Trung, T.N.; Hien, T.T.; Dao, T.T.; Yim, N.; Ngoc, T.M.; Oh, W.K.; Bae, K. Selected compounds derived from
moutan cortex stimulated glucose uptake and glycogen synthesis via AMPK activation in human HepG2
cells. J. Ethnopharmacol. 2010,131, 417–424.
84.
Zhao, G.; Shen, Y.; Ma, J.; Li, F.; Shi, X. Protection of polysaccharides-2b from mudan cortex of
Paeonia suffruticosa andr on diabetic cataract in rats. Zhongguo Zhong Yao Za Zhi
2007
,32, 2036–2039. [PubMed]
85.
Tatsumi, S.; Mabuchi, T.; Abe, T.; Xu, L.; Minami, T.; Ito, S. Analgesic effect of extracts of chinese medicinal
herbs moutan cortex and coicis semen on neuropathic pain in mice. Neurosci. Lett.
2004
,370, 130–134.
[CrossRef] [PubMed]
86.
Kim, H.G.; Park, G.; Piao, Y.; Kang, M.S.; Pak, Y.K.; Hong, S.P.; Oh, M.S. Effects of the root bark of
Paeonia suffruticosa on mitochondria-mediated neuroprotection in an MPTP-induced model of parkinson’s
disease. Food Chem. Toxicol. 2014,65, 293–300. [CrossRef] [PubMed]

Molecules 2017,22, 946 23 of 27
87.
Wu, J.B.; Song, N.N.; Wei, X.B.; Guan, H.S.; Zhang, X.M. Protective effects of paeonol on cultured rat
hippocampal neurons against oxygen–glucose deprivation-induced injury. J. Neurol. Sci.
2008
,264, 50–55.
[CrossRef] [PubMed]
88.
Su, S.-Y.; Cheng, C.Y.; Tsai, T.H.; Hsiang, C.Y.; Ho, T.Y.; Hsieh, C.L. Paeonol attenuates H
2
O
2
-induced
NF-
κ
B-associated amyloid precursor protein expression. Am. J. Chin. Med.
2010
,38, 1171–1192. [CrossRef]
[PubMed]
89.
Himaya, S.; Ryu, B.; Qian, Z.J.; Kim, S.K. Paeonol from hippocampus kuda bleeler suppressed the
neuro-inflammatory responses
in vitro
via NF-
κ
B and MAPK signaling pathways. Toxicol. In Vitro
2012
,26,
878–887. [CrossRef] [PubMed]
90.
Lin, C.; Lin, H.Y.; Chen, J.H.; Tseng, W.P.; Ko, P.Y.; Liu, Y.S.; Yeh, W.L.; Lu, D.Y. Effects of paeonol on
anti-neuroinflammatory responses in microglial cells. Int. J. Mol. Sci.
2015
,16, 8844–8860. [CrossRef]
[PubMed]
91.
Zhong, S.Z.; Ge, Q.H.; Qu, R.; Li, Q.; Ma, S.P. Paeonol attenuates neurotoxicity and ameliorates cognitive
impairment induced by D-galactose in icr mice. J. Neurol. Sci. 2009,277, 58–64. [CrossRef] [PubMed]
92.
Tseng, Y.T.; Hsu, Y.Y.; Shih, Y.T.; Lo, Y.C. Paeonol attenuates microglia-mediated inflammation and oxidative
stress–induced neurotoxicity in rat primary microglia and cortical neurons. Shock (Augusta Ga.)
2012
,37,
312–318. [CrossRef] [PubMed]
93.
Zhou, J.; Zhou, L.; Hou, D.; Tang, J.; Sun, J.; Bondy, S.C. Paeonol increases levels of cortical cytochrome
oxidase and vascular actin and improves behavior in a rat model of alzheimer’s disease. Brain Res.
2011
,
1388, 141–147. [CrossRef] [PubMed]
94.
Guo, R.B.; Wang, G.F.; Zhao, A.P.; Gu, J.; Sun, X.L.; Hu, G. Paeoniflorin protects against ischemia-induced
brain damages in rats via inhibiting MAPKs/NF-κB-mediated inflammatory responses. PLoS ONE 2012,7,
e49701. [CrossRef] [PubMed]
95.
Nam, K.N.; Yae, C.G.; Hong, J.W.; Cho, D.H.; Lee, J.H.; Lee, E.H. Paeoniflorin, a monoterpene glycoside,
attenuates lipopolysaccharide-induced neuronal injury and brain microglial inflammatory response.
Biotechnol. Lett. 2013,35, 1183–1189. [CrossRef] [PubMed]
96.
Liu, D.Z.; Zhu, J.; Jin, D.Z.; Zhang, L.M.; Ji, X.Q.; Ye, Y.; Tang, C.P.; Zhu, X.Z. Behavioral recovery following
sub-chronic paeoniflorin administration in the striatal 6-OHDA lesion rodent model of parkinson’s disease.
J. Ethnopharmacol. 2007,112, 327–332. [CrossRef] [PubMed]
97.
Liu, H.Q.; Zhang, W.Y.; Luo, X.T.; Ye, Y.; Zhu, X.Z. Paeoniflorin attenuates neuroinflammation and
dopaminergic neurodegeneration in the MPTP model of parkinson’s disease by activation of adenosine a1
receptor. Br. J. Pharmacol. 2006,148, 314–325. [CrossRef] [PubMed]
98.
Sun, R.; Wang, K.; Wu, D.; Li, X.; Ou, Y. Protective effect of paeoniflorin against glutamate-induced
neurotoxicity in PC12 cells via Bcl-2/bax signal pathway. Folia Neuropathol.
2012
,50, 270–276. [CrossRef]
[PubMed]
99.
Sun, X.; Cao, Y.B.; Hu, L.F.; Yang, Y.P.; Li, J.; Wang, F.; Liu, C.F. Asics mediate the modulatory effect by
paeoniflorin on alpha-synuclein autophagic degradation. Brain Res.
2011
,1396, 77–87. [CrossRef] [PubMed]
100.
Dong, H.; Li, R.; Yu, C.; Xu, T.; Zhang, X.; Dong, M. Paeoniflorin inhibition of 6-hydroxydopamine-induced
apoptosis in PC12 cells via suppressing reactive oxygen species-mediated pkc
δ
/NF-
κ
B pathway. Neuroscience
2015,285, 70–80. [CrossRef] [PubMed]
101.
Wang, D.; Tan, Q.R.; Zhang, Z.J. Neuroprotective effects of paeoniflorin, but not the isomer albiflorin, are
associated with the suppression of intracellular calcium and calcium/calmodulin protein kinase ii in PC12
cells. J. Mol. Neurosci. 2013,51, 581–590. [CrossRef] [PubMed]
102.
Fujiwara, H.; Tabuchi, M.; Yamaguchi, T.; Iwasaki, K.; Furukawa, K.; Sekiguchi, K.; Ikarashi, Y.; Kudo, Y.;
Higuchi, M.; Saido, T.C. A traditional medicinal herb Paeonia suffruticosa and its active constituent
1,2,3,4,6-penta-O-galloyl-
β
-D-glucopyranose have potent anti-aggregation effects on alzheimer’s amyloid
β
proteins in vitro and in vivo. J. Neurochem. 2009,109, 1648–1657. [CrossRef] [PubMed]
103.
Choi, B.M.; Kim, H.J.; Oh, G.S.; Pae, H.O.; Oh, H.; Jeong, S.; Kwon, T.O.; Kim, Y.M.;
Chung, H.-T. 1,2,3,4,6-penta-O-galloyl-
β
-D-glucose protects rat neuronal cells (neuro 2a) from hydrogen
peroxide-mediated cell death via the induction of heme oxygenase-1. Neurosci. Lett.
2002
,328, 185–189.
[CrossRef]
104.
Shon, Y.H.; Nam, K.S. Protective effect of moutan cortex extract on acetaminophen-induced hepatotoxicity
in mice. J. Ethnopharmacol. 2004,90, 415–419. [CrossRef] [PubMed]

Molecules 2017,22, 946 24 of 27
105.
Wu, J.; Xue, X.; Zhang, B.; Jiang, W.; Cao, H.; Wang, R.; Sun, D.; Guo, R. The protective effects of paeonol
against epirubicin-induced hepatotoxicity in 4t1-tumor bearing mice via inhibition of the PI3K/Akt/NF-
κ
B
pathway. Chem.-Biol. Interact. 2016,244, 1–8. [CrossRef] [PubMed]
106.
Hu, S.; Shen, G.; Zhao, W.; Wang, F.; Jiang, X.; Huang, D. Paeonol, the main active principles of Paeonia
moutan, ameliorates alcoholic steatohepatitis in mice. J. Ethnopharmacol.
2010
,128, 100–106. [CrossRef]
[PubMed]
107.
Chen, M.; Cao, L.; Luo, Y.; Feng, X.; Sun, L.; Wen, M.; Peng, S. Paeoniflorin protects against concanavalin
a-induced hepatitis in mice. Int. Immunopharmacol. 2015,24, 42–49. [CrossRef] [PubMed]
108.
Zhao, Y.; Ma, X.; Wang, J.; Zhu, Y.; Li, R.; Wang, J.; He, X.; Shan, L.; Wang, R.; Wang, L. Paeoniflorin alleviates
liver fibrosis by inhibiting HIF-1
α
through mtor-dependent pathway. Fitoterapia
2014
,99, 318–327. [CrossRef]
[PubMed]
109.
Espiritu, A.G.; Doma, B.T., Jr.; Wang, Y.F.; Camille, F. Efficacy of methanol extracts of mentha haplocalyx briq.
And Paeonia suffruticosa andr. For potential antibacterial activity. Sustain. Environ. Res. 2014,24, 319–324.
110.
Yang, J.F.; Yang, C.H.; Chang, H.W.; Yang, C.S.; Lin, C.W.; Chuang, L.Y. Antioxidant and antibacterial
properties of pericarpium trichosanthis against nosocomial drug resistant strains of acinetobacter baumannii
in taiwan. J. Med. Plants Res. 2009,3, 982–991.
111.
Hong, M.H.; Kim, J.H.; Na, S.H.; Bae, H.; Shin, Y.C.; Kim, S.H.; Ko, S.G. Inhibitory effects of Paeonia suffruticosa
on allergic reactions by inhibiting the nf-kappab/ikappab-alpha signaling pathway and phosphorylation of
erk in an animal model and human mast cells. Biosci. Biotechnol. Biochem.
2010
,74, 1152–1156. [CrossRef]
[PubMed]
112.
Zhai, T.; Sun, Y.; Li, H.; Zhang, J.; Huo, R.; Li, H.; Shen, B.; Li, N. Unique immunomodulatory effect of
paeoniflorin on type i and ii macrophages activities. J. Pharmacol. Sci.
2016
,130, 143–150. [CrossRef]
[PubMed]
113.
Zhao, Y.; Wang, B.E.; Zhang, S.W.; Yang, S.M.; Wang, H.; Ren, A.M.; Yi, E.T. Isolation of antifungal compound
from Paeonia suffruticosa and its antifungal mechanism. Chin. J. Integr. Med.
2015
,21, 211–216. [CrossRef]
[PubMed]
114.
Ishiguro, K.; Ando, T.; Maeda, O.; Hasegawa, M.; Kadomatsu, K.; Ohmiya, N.; Niwa, Y.; Xavier, R.;
Goto, H. Paeonol attenuates tnbs-induced colitis by inhibiting NF-
κ
B and stat1 transactivation. Toxicol. Appl.
Pharmacol. 2006,217, 35–42. [CrossRef] [PubMed]
115.
Chen, C.R.; Sun, Y.; Luo, Y.J.; Zhao, X.; Chen, J.F.; Yanagawa, Y.; Qu, W.M.; Huang, Z.L. Paeoniflorin promotes
non-rapid eye movement sleep via adenosine a1 receptors. J. Pharmacol. Exp. Therap.
2016
,356, 64–73.
[CrossRef] [PubMed]
116.
Sun, M.; Huang, L.; Zhu, J.; Bu, W.; Sun, J.; Fang, Z. Screening nephroprotective compounds from cortex
moutan by mesangial cell extraction and uplc. Arch. Pharma. Res.
2015
,38, 1044–1053. [CrossRef] [PubMed]
117.
Zhu, J.L.; Huang, L.M.; Wen-Jie, B.U.; Kai, G.Q.; Fan, H.W.; Xian-Hua, L.I.; Sun, M. Analysis of bioactive
components in moutan cortex by mesangial cell membrane immobilized chromatography. J. Anhui Univ.
2013,37, 104–108.
118.
Comparative Studies on Pharmacopoeial Definitions, Requirements and Information for Crude Drugs among
FHH Member Countries in 2007. Available online: http://www.nihs.go.jp/dpp/FHH/FHH.htm (accessed
on 5 June 2017).
119.
El Babili, F.; El Babili, M.; Fouraste, I.; Chatelain, C. Peonies: Comparative study by anatomy and tlc of three
traditional chinese medicinal plants. Chin. Med. 2013,4, 166–172. [CrossRef]
120.
Zhang, R. Application of tlc characterastic chromatography in the quality control of cortex moutan. CJTCM
2013,25, 539–541.
121.
Xu, S.J.; Yang, L.; Zeng, X.; Zhang, M.; Wang, Z.T. Characterization of compounds in the chinese herbal drug
Mu-Dan-Pi by liquid chromatography coupled to electrospray ionization mass spectrometry. Rapid Commun.
Mass Spectrom. 2006,20, 3275–3288. [CrossRef] [PubMed]
122.
Zhang, Z.-Q. HPLC with uv switch determination of 8 indicative components in combination extracts of
persicae ramulus and paeoniae radix alba. Chin. J. Pharm. Anal. 2013,33, 1899–1903.
123.
Wang, S.; Huang, J.; Mao, H.; Wang, Y.; Kasimu, R.; Xiao, W.; Wang, J. A novel method HPLC-DAD analysis
of the contentsof moutan cortexand paeoniae radix alba with similar constituents-monoterpene glycosides
in guizhi fuling wan. Molecules (Basel Switzerland) 2014,19, 17957–17967. [CrossRef] [PubMed]

Molecules 2017,22, 946 25 of 27
124.
Ding, Y.; Wu, E.; Chen, J.; Nguyen, H.T.; Do, T.H.; Park, K.L.; Bae, K.H.; Kim, Y.H.; Kang, J.S. Quality
evaluation of moutan cortex radicis using multiple component analysisby high performance liquid
chromatography. Bull. Korean Chem. Soc. 2009,30, 2240–2244.
125.
Chunnian, H.; Yong, P.; Yuxiong, F.; Bing, P.; Zhe, W.; Peigen, X. Quick comparison of radix paeonia
alba, radix paeonia rubra, and cortex moutan by high performance liquid chromatography coupled with
monolithic columns and their chemical pattern recognition. Pharmacogn. Mag. 2012,8, 237. [PubMed]
126.
Wu, M.; He, Y.; Tang, L.; Wang, Z. Clustering analysis of HPLC chromatographic fingerprints of
Paeonia suffruticosa.Zhongguo Zhong Yao Za Zhi 2007,32, 1054–1056. [PubMed]
127. Hu, Y.-F.; Xu, Q.; Xu, G.-B.; Jiang, L.; Wu, H. Comparison of UPLC fingerprint of cortex moutan before and
after stir-frying. China Pharm. 2015,26, 800–802.
128.
Fan, X.; Wang, Z.; Li, Q.; Ma, T.; Bi, K.; Jia, Y. UPLC characteristic chromatographic profile of moutan cortex.
Zhongguo Zhong Yao Za Zhi 2011,36, 715–717. [PubMed]
129.
Ye, J.; Zhang, X.; Dai, W.; Yan, S.; Huang, H.; Liang, X.; Li, Y.; Zhang, W. Chemical fingerprinting of liuwei
dihuang pill and simultaneous determination of its major bioactive constituents by HPLC coupled with
multiple detections of DAD, ELSD and ESI-MS. J. Pharm. Biomed. Anal.
2009
,49, 638–645. [CrossRef]
[PubMed]
130.
Luo, N.; Ding, W.; Wu, J.; Qian, D.; Li, Z.; Qian, Y.; Guo, J.; Duan, J. UPLC-Q-TOF/MS coupled with
multivariate statistical analysis as a powerful technique for rapidly exploring potential chemical markers to
differentiate between radix paeoniae alba and radix paeoniae rubra. Nat. Prod. Commun.
2013
,8, 487–491.
[PubMed]
131.
He, Q.; Ge, Z.W.; Song, Y.; Cheng, Y.Y. Quality evaluation of cortex moutan by high performance liquid
chromatography coupled with diode array detector and electrospary ionization tandem mass spectrometry.
Chem. Pharm. Bull. 2006,54, 1271–1275. [CrossRef] [PubMed]
132.
Song, Y.; He, Q.; Li, P.; Cheng, Y.Y. Capillary high performance liquid chromatography coupled with
electrospray ionization mass spectrometry for rapid analysis of pinane monoterpene glycosides in cortex
moutan. J. Sep. Sci. 2008,31, 64–70. [CrossRef] [PubMed]
133.
Deng, X.M.; Yu, J.Y.; Ding, M.J.; Zhao, M.; Xue, X.Y.; Che, C.T.; Wang, S.M.; Zhao, B.; Meng, J. Liquid
chromatography-diode array detector-electrospray mass spectrometry and principal components analyses
of raw and processed moutan cortex. Pharmacog. Mag. 2016,12, 50.
134.
Li, X.Y.; Duan, S.M.; Liu, H.H.; XU, J.-D.; Kong, M.; Liu, H.Q.; Li, S.L. Sulfur-containing derivatives as
characteristic chemical markers in control of sulfur-fumigated moutan cortex. Acta Pharm. Sin.
2016
,51,
972–978.
135.
Gao, X.; Sun, L.; Qiao, S.; Gao, S.; Che, Y.; Zhang, K. HPLC fingerprint of liuwei dihuang condensed pills.
Zhongguo Zhong Yao Za Zhi 2012,37, 3411–3415. [PubMed]
136.
Lu, X.; Zhao, X.; Bai, C.; Zhao, C.; Lu, G.; Xu, G. LC-MS-based metabonomics analysis. J. Chromatogr. B
2008
,
866, 64–76. [CrossRef] [PubMed]
137.
Li, X.Y.; Xu, J.D.; Xu, J.; Kong, M.; Zhou, S.S.; Mao, Q.; Brand, E.; Chen, H.B.; Liu, H.Q.; Li, S.L.
Uplc-qtof-ms based metabolomics coupled with the diagnostic ion exploration strategy for rapidly evaluating
sulfur-fumigation caused holistic quality variation in medicinal herbs, moutan cortex as an example.
Anal. Methods 2016,8, 1034–1043. [CrossRef]
138.
Xiao, C.; Wu, M.; Chen, Y.; Zhang, Y.; Zhao, X.; Zheng, X. Revealing metabolomic variations in cortex moutan
from different root parts using HPLC-MS method. Phytochem. Anal. 2015,26, 86–93. [CrossRef] [PubMed]
139.
Liu, J.H.; Sun, H.; Zhang, A.H.; Yan, G.L.; Han, Y.; Xue, C.S.; Zhou, X.H.; Shi, H.; Wang, X.J. Serum
pharmacochemistry combined with multiple data processing approach to screen the bioactive components
and their metabolites in mutan cortex by ultra-performance liquid chromatography tandem mass
spectrometry. Biomed. Chromatogr. 2014,28, 500–510. [CrossRef]
140.
Jiang, Y.; David, B.; Tu, P.; Barbin, Y. Recent analytical approaches in quality control of traditional chinese
medicines—A review. Anal. Chim. Acta 2010,657, 9–18. [CrossRef] [PubMed]
141.
Hu, Y.F.; Wu, D.L.; Xu, G.B. Comparative analysis of moutan cortex extract collected from five regions by
GC-MS and chemometrics. Chin. Tradit. Patent Med. 2015,37, 2003–2007.
142.
Ganzera, M. Quality control of herbal medicines by capillary electrophoresis: Potential, requirements and
applications. Electrophoresis 2008,29, 3489–3503. [CrossRef] [PubMed]

Molecules 2017,22, 946 26 of 27
143.
Wu, Y.T.; Huang, W.Y.; Lin, T.C.; Sheu, S.J. Determination of moutan tannins by high-performance liquid
chromatography and capillary electrophoresis. J. Sep. Sci. 2003,26, 1629–1634. [CrossRef]
144.
Yu, K.; Wang, Y.; Cheng, Y. Determination of the active components in chinese herb cortex moutan by MEKC
and LC. Chromatographia 2006,63, 359–364. [CrossRef]
145.
Holland, L.A.; Leigh, A.M. Amperometric and voltammetric detection for capillary electrophoresis.
Electrophoresis 2002,23, 3649–3658. [CrossRef]
146.
Chen, G.; Zhang, L.; Zhu, Y. Determination of glycosides and sugars in moutan cortex by capillary
electrophoresis with electrochemical detection. J. Pharm. Biomed. Anal.
2006
,41, 129–134. [CrossRef]
[PubMed]
147.
Gang, C.; Zhang, L.; Pengyuan, Y. Determination of three bioactive constituents in moutan cortex by capillary
electrophoresis with electrochemical detection. Anal. Sci. 2005,21, 1161–1165.
148.
Chen, G.; Zhang, L.; Wu, X.; Ye, J. Determination of mannitol and three sugars in ligustrum lucidum ait.
By capillary electrophoresis with electrochemical detection. Anal. Chim. Acta 2005,530, 15–21. [CrossRef]
149.
Tanaka, R.; Shibata, H.; Sugimoto, N.; Akiyama, H.; Nagatsu, A. Application of a quantitative 1h-nmr method
for the determination of paeonol in moutan cortex, hachimijiogan and keishibukuryogan. J. Nat. Med.
2016
,
70, 797–802. [CrossRef] [PubMed]
150.
Wang, P.; Rong, Z.M.; Ma, C.X.; Zhao, X.F.; Xiao, C.N.; Zheng, X.H. Distribution of metabolites in root barks
of seven tree peony cultivars for quality assessment using nmr-based metabolomics. Chin. Herb. Med.
2017
,
9, 31–41. [CrossRef]
151.
Zhao, S.Q. Fourier Transform Infrared(ftir) Spectroscopy Investigation of Tree Peony Flowers and Cortex
Moutan. Master ’s Thesis, Yunnan Normal University, Yunnan, China, 2015.
152.
Yang, S.; Qu, L.; Yang, R.; Li, J.; Yu, L. Modified glassy carbon electrode with nafion/mwnts as a
sensitive voltammetric sensor for the determination of paeonol in pharmaceutical and biological samples.
J. Appl. Electrochem. 2010,40, 1371–1378. [CrossRef]
153.
Dong, W.; Shen, H.B.; Liu, X.H.; Li, M.J.; Li, L.S. Cdse/zns quantum dots based fluorescence quenching
method for determination of paeonol. Spectrochim. Acta Part A Mol. Biomol. Spectrosc.
2011
,78, 537–542.
[CrossRef] [PubMed]
154.
Chen, Z.; Chen, J.; Liang, Q.; Wu, D.; Zeng, Y.; Jiang, B. Znse quantum dots based fluorescence quenching
method for determination of paeoniflorin. J. Lumin. 2014,145, 569–574. [CrossRef]
155.
Jiang, L.; Yunfei, H.U.; Pei, Y.; Guobing, X.U.; Deling, W.U.; Qian, X.U.; Pharmacy, S.O. Comparation of
inorganic elements in paeonol saffuruticosa from different origins by ICP-MS/ICP-OES combined with
chemometrics technology. China Pharmacy 2016,27, 1249–1253.
156.
Liu, W.; Wang, Z.; Hu, J.; Li, J.; Zhang, Z.; Xiao, W. Morphological analysis and dissolution characteristics
analysis of 24 trace elements in Paeonia suffruticosa.Chin. J. Exp. Tradit. Med. Formulae 2016,22, 60–65.
157.
Zhuang, H.; Ni, Y.; Kokot, S. Combining HPLC-DAD and ICP-MS data for improved analysis of complex
samples: Classification of the root samples from cortex moutan. Chemom. Intell. Lab. Syst.
2014
,135, 183–191.
[CrossRef]
158.
Guo, M.; Chen, W.; Xu, Y. The implication of trace elements on the quality of cortex moutan. China J. Chin.
Mater. Med. 2008,33, 1083–1085.
159.
Hon, K.L.; Chan, B.C.-L.; Leung, P.C. Chinese herbal medicine research in eczema treatment. Chin. Med.
2011,6, 17. [CrossRef] [PubMed]
160. Sheng, Z.H.; Yu, C.H.; Wu, Q.F. Determination of peoniflorin and benzoic acid in duration of cultivation of
plant in radix paeoniae rubra. Chin. Arch. Tradit. Chin. Med. 2008,5, 103.
161.
Baye, H.; Hymete, A. Lead and cadmium accumulation in medicinal plants collected from environmentally
different sites. Bull. Environ. Contam. Toxicol. 2010,84, 197–201. [CrossRef] [PubMed]
162.
Qian, G.; Rimao, H.; Xingqin, W.; Xin, M. Simultaneous determination of organochlorines and pyrethroid
pesticide residues in cotex moutan based on matrix solid phase dispersion and gas chromatography.
Chin. Agric. Sci. Bull. 2012,21, 242–247.
163.
Liu, Y.; Xia, Y.; Guo, P.; Wang, G.; Shen, Z.; Xu, Y.; Chen, Y. Copper and bacterial diversity in soil enhance
paeonol accumulation in cortex moutan of Paeonia suffruticosa ‘fengdan’. Hortic. Environ. Biotechnol.
2013
,54,
331–337. [CrossRef]
164.
Tokalıo˘glu, ¸S. Determination of trace elements in commonly consumed medicinal herbs by ICP-MS and
multivariate analysis. Food Chem. 2012,134, 2504–2508. [CrossRef] [PubMed]

Molecules 2017,22, 946 27 of 27
165.
Deng, B. Determination of trace metals Fe, Zn, Cu and mn in cortex moutan by atomic absorption
spectrometry. Chin. J. Spectrosc. Lab. 2008,25, 630–632.
166.
Guan, D.P.; Wan, Q.; Wu, L. Cortex moutan harmful heavy metal element detection. Chin. J. Ethnomed.
Ethnopharm. 2015,24, 20–21.
167.
Liu, X.H. Analysis of heavy metal elements lead and cadmium in cortex moutan and its planting soil.
Chin. J. Spectrosc. Lab. 2013,30, 821–824.
168.
Liang, X.; Li, H.; Li, S. A novel network pharmacology approach to analyse traditional herbal formulae:
The Liu-Wei-Di-Huang pill as a case study. Mol. BioSyst. 2014,10, 1014–1022. [CrossRef] [PubMed]
169.
Zhang, D.Q.; A-Li, M.A.; Yang, Y.S.; Huang, C.H.; Zhou, N. Content determination of trihydroxybenzoic acid
and paeonol in Paeonia delavayi from different producing area by HPLC. Chin. J. Exp. Tradit. Med. Formulae
2014,20, 57–60.
170.
Zhang, Y.; Liu, X.; Zhang, Y. Determination of paeonol in cortex moutan by HPLC. Heilongjiang Med. J.
2010
,
23, 151–153.
171.
Li, Y.G.; Song, L.; Liu, M.; Wang, Z.T. Advancement in analysis of salviae miltiorrhizae radix et rhizoma
(danshen). J. Chromatogr. A 2009,1216, 1941–1953. [CrossRef] [PubMed]
©
2017 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access
article distributed under the terms and conditions of the Creative Commons Attribution
(CC BY) license (http://creativecommons.org/licenses/by/4.0/).